See if you are into exercising. Find something you love. Not everyone love weightlifting or jogging so try to find something you enjoy and better if you find a partner. The point is from my experience human vitality does not decrease continuously buy drops sharply after certain age. On my side it was 28 and 35.
Take care of joints and teeth. Once they degenerate it's impossible to reverse the process.
Get financials straight. Know tricks to increase your credit score and keep it as high as you can. Also knows to invest a bit and make sure not to borrow money to invest because you are probably not that good.
Find something you can spend a life on. Something fundamental such as astronomy, mathematics, physics, geology, etc. The point is not to excel at these things, but to find consolence when you feel being ditched by the whole world. Reason I recommend those topics because not only you understand the world better after studying them but your mind will be sharper. Also look into like learning music (guitar, piano, etc.), painting, writing (novels, poetry, short stories, comics, etc.) and other forms ofc...
Stay away from gambling unless you are very disciplined. And if you do, don't play against the house and don't borrow money to gamble.
Stay away from drugs. Maybe stay away from smoking too. You don't need those for "artistic inspiration" or other enhancements. Exercising and reading get you much further. Enhancements through medication also bring side effects in the long run.
Build your personal brand. Be sound and reasonable. Knows how to communicate effectively. Learn to speak in public. Soft skills are tough to pick up and grow.
Start investing. You don’t have to learn a ton about picking stocks — start by consistently putting money into a robo-advisor like Wealthfront or Betterment. This compounds; a small amount of money invested now will be more impactful than a large amount of money invested later.
If your job offers a 401k, contribute as much as possible. If you can afford it, max it out. This also compounds.
Appreciate your body. Years down the line, you will have to expend a lot of money and effort to look the way you look right now for free. I used to love having long hair in my teens and early 20s; now I need to take hair loss drugs. Related: start exercising. The aforementioned money and effort will be much less if you build up good exercise habits now.
Learn to cook. Cook a variety of things. This saves money and becomes more important socially as you age.
Take a hobby seriously. I’ve played guitar for almost 15 years, but haven’t tried to really up my technical skills until recently, and now there’s a long road ahead of me until I can play what I want. Whatever you decide to do, when you get serious about it you’ll wish you had done so years prior. Related: if you’re in tech, finish your side projects. It takes a lot of dedication, especially in the home stretch, but it’s much more satisfying to be able to point to one finished thing you made than a dozen abandoned works in progress.
Music and/or drawing. These are both long curve activities where the more you put in, the more you get out. For example, fooling around with a ukulele for a year or two really improved my guitar later (especially fingerpicking!) when I wanted to get more serious about it. Even though I'm still not very good, I'm not trying to be a rockstar or a professional musician, and I can do a lot of nice things with it. Now I'm re-learning music theory I was told about in high school, and it's feeling interesting and useful.
It's very much an enriching experience that constantly feels worthwhile, but it's been years in unfolding for me. These things build over time just as much as interest does on bank accounts.
Start saving, even for very small amounts. Compound interest can work wonders.
Start seeing a dentist every ~6 months. You won't have any issues for many years, so you may think that it's wasted time/money, but one day things will start going downhill and you will be prepared. Note that many tooth or gum issues cannot be reversed. Beware of what you put into your mouth. Too much chocolate/sugar? To much acidic food/citrus? Take care. Take things in moderation.
As someone else mentioned, don't be afraid to experiment. You will mostly regret the things you haven't done, not the other way around.
Take care of yourself, try to stay fit, but don't worry about the things you do wrong too much.
Because folks in their 20s are usually in a process of self-discovery / growth / change, try to develop the habit of making sure you are investing in friendships that matter and are aligned with your goals. This sounds cold and calculating, but learning to step away from toxic/misaligned friendships and double down on friendships / connections / mentorships that dovetail with and proactively (and symbiotically) support your goals is one of the most difficult-to-measure super powers. It doesn't pay immediate dividends, but if you look at most successful / accomplished people, you realize they're skilled at doing this (implicitly or not).
Speaking of negative loops: personally, I found removing alcohol from my diet to be one of the simplest and most profound overall quality-of-life upgrades.
And don't worry too much about investing. Open a Schwab / Etrade account and put $100 in it. Just break the "investing seal." Treat it like a little savings account to start with. And then slowly add to your portfolio. The critical step is making the account. This will allow future decisions to flow more easily.
Don't hesitate to move locations if that can improve your career or other prospects. This gets progressively harder to do later in life.
Get to know people who are 5 and 10 years ahead of you in your career track. This will push you out of your bubble of same age peers.
There's a high likelihood that you're wrong about many things about the world in your 20's. The effect of cognitive biases (read up on them) is also non-negligible at this age. So make sure you have a feedback mechanism to validate whatever it is that you think are learning. Otherwise it's possible to be wrong about things for years without realizing it.
Learn at least one hard skill that can be measured objectively in some way (if you haven't already). It could be programming, maths, music, sports etc. Once you know what it feels like to genuinely learn something, you're less likely to fool yourself when learning other things later in life.
Develop friendships and other relationships if you find people you gel with.
Don't get too out of whack, health wise. Try a bunch of physical activities until you find one you enjoy doing on a regular basis.
20s are a time when you are at the bottom of the power hierarchy in the corporate world and probably socially and politically as well. So beware of anti-authority, outsider-types figures who'll use this resentment to sell you simplistic solutions to everything. At the same time, keep in mind that power corrupts. Chesterton's fence and all that.
Read every damn day. Read in your field proactively - stuff you don't need to know yet. Read stuff tangentially related to your field. Read the stuff most people in your field don't know (sales! business! negotiation! psychology!) This has been the bedrock of my entire career. I now make a comfortable upper middle class salary working 20-24h a week as a consultant, allowing me to do grad school in areas of personal interest, and I didn't even do comp sci in uni, or start programming professionally until I was 30. But I probably read 1-2 hours a day and have read a lot over the last three decades. It has paid off massively. Learning to write is important too, but recently there has been a trend in telling everyone they need to write daily. If you write more than you read, you're doing it wrong and are probably a shit writer wasting your time. (Real Writers who have done an extended period of MASSIVE reading excluded..)
Learn soft skills: writing, communicating, negotiating, reading a room. I did this by doing door to door canvassing in my 20's for an environmental group, haha. Trial by fire. Once you've spent some time hitting rich folks in West Vancouver for money to save trees, you aren't afraid of any meeting. (No German Shepherd ready to roam out onto the road and scare me off? I got this.)
Have a hobby that you can build a life-long practice habit around. I recommend this be something that you don't plan to pivot your career to so you don't ever take your eyes off long term development for short term gain. Music is a popular one, but there are lots of other options. The point of it is to get good and consistent at highly focused solitary skill development. Warren Buffet famously credited playing an instrument as his biggest advantage. I've taught a bunch of juniors to code now, and the ones who already had this skill basically had rockets on their feet. One of my friends who has been a silicon valley exec many times over said "I always hire the musicians".
Lots of other things are important, but for me, those are the big three. Start doing those now and you'll have a very attractive career in your 30's and 40's.
Build a reading habit. Books have evolved as a central tenet of knowledge preservation of societies for a reason - they contain a lifetime of wisdom in a few hours of consumption. Read books that are 10+ years old, like High Output Management, The Mythical Man Month, and Good Strategy / Bad Strategy. They’re written by people who have done great things and condensed great lessons, don’t underestimate the depth of the words and revisit them often! Regarding books: the older, the better. There's a reason they're still around. Read the classics. Other advice: consistency is key to be good at anything. It's better to do 5 or 10 minutes a day every day than once a month for a full day.
Make at least 2 really close friends that you can tell anything, preferably outside of work. You can make friends at work, just make sure you keep the friendship and hang out afterwards since work can distort relationships. As you get older it’s generally harder to make friends, but just as important to have them - so make them young!
Exercise is great, has been mentioned multiple times. Carve out an hour a week, start small, but be consistent. Healthy body = healthy mind!
Friends and family and community. This is actually more important than all other advice in this thread (I never say that kind of thing, but it's true here). They will be there for you when you can't be there for yourself. The HN community is giving good advice, and a community that knows you personally will give you even better advice. Modernity is hard on friendships and community so it takes some work to get started and maintain.
Exercise. In your 20s, someone who lifts is just bigger. In your 30s and 40s, someone who lifts is actually fitter, and it diverges from there.
Music. I have just started learning piano. "Where has this been all my life?" The skill compounds, and it's a huge help.
Meditation, if you can avoid the mainstream stuff.
Nic Carter said offhandedly, "I think writing is one of the most high leverage activities available to young people". What a brilliant observation! Learn about urbanism because you'll have to choose many places to live. Don't get drunk and then lose the next day because you have a hangover. Learn to read books on your laptop (I like amazon cloud reader with OLED laptop), so you can have less physical stuff to move. Learn at least one crowd-pleaser meal so you can invite people over for dinner. Buy assets. Switch jobs every year (its a dumb system but this is how you increase your pay).
Travel when you’re young. Get a working holiday visa in Canada, Australia, Japan or UK. Go live.
Exercise! Can’t emphasize this enough! Makes you happier and healthier. Also a harder habit to adapt later in life.
Don’t do drugs, gamble, drink, or watch tons of porn.
Do read. Books. Not kindles. Books.
Be part of a regular community. That could be church, a sports team, chorus, etc.
Invest. Put money in an SP500 index fund. Especially if retirement accounts available.
Don’t be an asshole.
If you need therapy, get therapy. Take a Carnegie course. Even taking etiquette lessons can help.
Learn to cook. You’ll save so much money and eat much better food.
Get a pet. Having a pet is a lifestyle, and a good one.
Consider having kids. It’s rare people say “I wish I never had children.” Early 20s might be too early, but there’s no perfect time.
Also, have fun!
There are already many great suggestions from others with a number of positive things you can do that will most likely have a good impact on your future, now it's all about you making choices. I'll give you just one and a simple one that I found to be an essential building block when growing up and trying to make sense out of things around which can sometimes become overwhelming. Exercise independent thought and awareness of yourself (self-inquiry) and those around you. Give yourself time to do it, sink it in. Time invested in understanding yourself will bring great appreciation for life which will lay a solid foundation for all the positive things to come in your future.
Don't be afraid to experiment, but "partying" should be kept to a minimum and only for socializing. Also, avoid debt as much as you realistically can. If you're taking out loans for school, don't be afraid to pick up a flexible part time job doing retail or waiting tables (this helped me keep my student loans much lower than they could have been). Source: personal experience. In my opinion partying that makes you happy should be kept at maximum in your 20'. That doesn't mean you should overconsume alcohol and substances. Go out, meet new people, have fun. Travel and party at various places around the world. Experience.
Warning: focusing on your retail job during school to reduce loans is a local optimization, not a global one. Minimum wage is low and a high salary can make very short work of loans. Study hard and work even harder on your internships. Career relevant experience is king.
Debt is a tool and nothing to fear if you know how to use it. Many fortunes have been made with debt. Many lost as well. The key is knowing that you're using a tool. It seems to me that many people just start borrowing, the same way they suddenly start being attracted to the opposite sex. "Oh, it's just a mortgage, and house prices go up." "It's just my second credit card, of course I can pay it off in three weeks." Good debt is a conscious decision, made when there's a strategy, not as a default path. Overall, it seems prudent to ask people in general to not go into debt, so they are more willing to think it through. Rather than just going with the flow because the store clerk said "you can walk out of here with both the jewelry and a credit card with a $20k limit!"
And the drugs, yeah that's pretty spot on. Careful with those.
Exercise - helps you think better, helps you feel better, helps you emotionally. Find something you like doing - I do power lifting and yoga - and get in the habit of doing it daily.
Explore - odds are your career isn’t really going to take off until your late 20s at the earliest, because frankly until then you’re just not going to be very good. Spend the time to learn everything you can from everyone you can and try anything you can - experience now pays dividends later. Accept that you’re young and inexperienced, be humble, don’t pretend you know what you’re doing when you don’t, and you’ll come out of this decade miles ahead of where you start.
Oh, and - you’ve got 60 years ahead of you, statistically speaking. Probably no more, probably no less. Plan accordingly.
Decide where you want to be after you retire. If you want to lie on a beach all day or travel the world, it's probably easier to get a job that lets you do that instead of waiting for later. In many cases you can achieve your goals with an order of magnitude less savings, and often optimizing for higher income may be counterproductive.
Don't spend 4 or more years in college for nothing. The degree greatly helps you accumulate points for Immigration to Canada, Australia or other countries if you decide to immigrate later in your life. Use college time as a time to cultivate lifelong friendships with worthwhile people.
I would say finish university (if you haven't), it should give you good theoretical knowledge in the field you want. Also learn other languages. These are things that are more difficult to learn later.
In general, in those years, you should take biggest risks and try to do/learn the most difficult stuff you can find and you are interested in. Do not prematurely tie yourself to a job that doesn't provide a sufficient challenge. (You can always make more money later.)
The life is a negotiation with reality about what you can accomplish. Do not set your initial offer too low.
Unless you have a good network of friends in the area where you plan to live long-term, start making more friends or find a social hobby which can give you an instant network where you move. (Dancing worked for me, but sport clubs or other events should work too). It's much harder to make friends in your 30s when people spend more time with their families. No experience with 40s yet, but extrapolating, I suspect it becomes close to impossible :)
Think for yourself, don't take for granted what others are saying. Prevalent opinions in society can be wrong. Herds aren't always right.
Learn as much as you can.
Be curious.
Start investing early.
Read. This will get you an edge against most people today.
Enjoy life.
Be kind.
Here are some things that may help your quality of life several decades from now.
Financial health:
* Start saving a large chunk of your income and invest it wisely in assets that will provide value over the long term. Avoid get rich quick schemes.
Physical health:
* Exercise everyday, preferably for a minimum of 30 minutes (it doesn't have to be a single session).
* Eat well, meaning, you can eat in tasty and highly indulgent foods, but develop the habit to eat more of whole and unprocessed/minimally processed foods.
* Related to the previous point, cooking is a life skill that will help manage your budget and health better. Learn to cook and try to cook at least one meal a day, if not all meals for the day.
* Sleep well and rest well during your waking hours.
Mental health:
* Related to the point about sleep and rest, try to regularly review your interactions online and offline, and cut off those that are not productive or those that make you feel worse, increase stress, etc. Good relationships can uplift you a lot, and bad relationships can make every other achievement pointless.
* Try out meditation, and if you're sure about your mental health, try a meditation retreat (even once is enough for a different perspective).
* It's natural to get extremely angry and upset about many things in this world. Practice some detachment if possible (this depends on your background and situation).
Odds and ends:
* Measure and track what you value. Without measurement, you won't realize how far you've reached or how far you've deviated from your desired states.
* Enjoy life through whatever provides you joy. Don't get guilt tripped by others on this front.
* Though related to health, I'm keeping this for the last since it may be very controversial. Avoid or drastically minimize the consumption of alcohol, smoking, and also caffeine if you can. The accumulated damage from these over decades cannot be reversed (well, if you have good genes, then it's a different matter).
Keep yourself fit. Get a workout program and stick with it. Eat well. Educate yourself financially. Understand how to save, invest etc. Build a good network of mentors, friends etc. who you can talk to in the long term. Build a closer tribe of close friends who you interact with more frequently. Reject fear (since piece of advice I'd give my 23 year old self). Stay aggressive. And don't forget to enjoy the results of the above. :)
Read biographies of great people across all walks of life. Personally I got a great deal from reading about Thomas Edison, Richard Feynman, Winston Churchill, Nikola Tesla, etc. Also basic psychology, e.g. cognitive biases, Maslow's Pyramid, physiology. Watch documentaries about various industries, manufacturing, construction, etc. Understand basic accounting and finance principles.
Exercise every day.
Meet one new person everyday.
Nurture your older relationships and don't let it falter.
Spend an hour learning everyday. Newspapers, courses, skills.
Travel regularly to see new places and people.
Be open minded. Don't imprison yourself in your beliefs, values, judgment.
Write a one-page journal every night before sleep.
Find joy in simple regular everyday things by practicing mindfulness. Food, sleep, nature, hikes, music, play.
Meditate 20 minutes a day.
Save half of your money and invest in all-world diversified stock market and never sell.
Start writing things down. If you have a terrible memory like me you might regret not documenting more of your life, especially because so many things happen in your 20s. I've started a weekly journal in my 30s and I'm so happy that I did. It's also worth doing the same for things at work. Having a few stories written down about features you've implemented or bugs you've fixed may help you get through a few interviews.
Take care of your teeth (drop soda) and skin. Exercise too.
Travel as much as you can. Get a job abroad if you can.
Study languages. They compound: french will make your English richer, Spanish will make it easier to get into French, Russian will make you understand some of the other slavic languages, etc. English, Spanish, Russian, and French cover a large portion of the earth. Also, as you get into a language and its culture, your understanding of the world will grow.
Get wild, just don’t make permanent mistakes like taking hard drugs or getting killed in a car accident.
The "boring things" that compound over time like - a fitness routine - yearly check ups with your physician and dentist - invest 10% of what you earn (no matter how little it may be but make it a habit)
Learn how your mind works (eg. read "waking up" by sam harris and know that people don’t think as much about you as you might think. Therefore don’t spend money you don’t have to impress them.
Keep learning in general and have fun in your profession - not in "fun every day" but don’t become one of those people who drag themselves to work just to make ends meet.
Travel within your means. There is a lot of fun in learning about different cultures. The best way is not so sit in a pricy hotel room.
Keep strong relationships with friends and family if possible. A supportive network of people that care about you can be very hard to build when your older and might be worth more than money some times in your life.
You‘re going to do better than a lot of your peers with these simple things.
Find something to stay curious about.
Start a family. Have kids. Maintain relationships with family members. Get married, have multiple kids. Or not! Not everyone can have or will have kids. Your life can be awesome without marriage. Your marriage can be awesome without kids. Finally some real advice. Go out, meet people, fall in love. True. Having children is the most meaningful thing anyone can do in their life.
Not comprehensive, but do this and you'll be light years ahead of everyone else your age (in order of importance).
Learn how money works, I don't mean how you buy stuff with it, but how money and debt actually work. If you get this squared away now you'll be better off than 80-90% of everyone else, it does taking a bit of a more pessimistic (realist) mindset. If you don't know where uncollectable financed debt goes or how financial instruments work to lower your monthly costs, or how your wages compare year over year in real purchasing power (i.e. whether you are making less the longer you stay at a job) then you don't know enough. Most people fall into a usury trap set by predatory banking institutions at some point.
Always risk manage big decisions and figure out what the ROI is for those decisions ahead of time. Do your research. Have a plan of action before you do something that locks you in for longer than a year. Don't trust the salesperson.
If a college degree you are interested in doesn't have a good ROI, don't major in it, or consider traveling internationally to a school where the ROI makes sense. You need to have your education paid off by the time you are 28-30 without outside help and promises of jobs at graduation are often fluff, consider the risks as well (are there hidden factors that might prevent graduation within a time period just as an example).
Learn how to negotiate, constantly determine whether they have credibility. If you are too agreeable you can't leverage the things you'll need later, and there is no basis for further negotiation when one party lacks credibility. Being able to walk away is valuable. Don't get caught in a circular logic trap, you decide what you want to do and no one else, you don't need to explain why because if they can't respect the decision then you have nothing to talk about because they've lost credibility.
Don't get taken advantage, your time is valuable, many people in their 20s discount their professional experience and subsequently get paid much less, or worked more; most places take advantage at some point unless you reasonably push back, as an example this can include sudden changes to shifts where they know you have prior commitments but they call and ask anyway (i.e. classes). Be wary of illusory promises as well and learn about the psychology and tactics you might face from these influencers. Understand Burnout and what you need to do to fix it.
Learn how to communicate effectively in writing at a professional level. Spelling, grammar, punctuation, and word choice all affect interactions. People will treat you differently based on how you present yourself (that includes appearance, odor, speech as well).
If you make a mistake, own it. Ask questions, improve, don't own/accept something that isn't your mistake.
Learn how to effectively learn and build the long term habits you'll need later, whether that's adjusting your diet or something else. (hint, don't give yourself the choice whether you follow through but have criteria/rules for exceptions and understand attention is finite, do what you need to structure the change accordingly).
Learn how to deal with liars and how to hold them accountable and don't lie. Almost all interactions moving forward will have some small lie where they can't easily be held accountable (Document details, memorialize, in writing, case-build, who you spoke to, when, what, etc) and fight for the rights have. If you are working to deal with an issue, realize what people can and can't do at various levels. Customer support, corporate, overseeing regulatory body, congressional representative that supports or oversees the area.
Build Discipline and other habits which make doing new things easier.
Be able to defend yourself, take Brazilian Jui Jitsu as a starter (this builds discipline), then some firearms training to understand how accurate guns are and how they work and are used.
Be able to survive, know how to start a fire that burns 8 hours without attention (putting a log on) and what you can and can't eat, how to prepare emergency food that doesn't need refrigeration, and what kind of preparations you need if the supply chain breaks down for necessities (shelter, water, food, safety).
Spend some time at the library reading up on historic events, everything happens in regular cycles, knowing and preparing to capitalize on certain events can ensure your safety and future prosperity. Also, most of the history you learned in high school if its US based is likely a biased narrative and useless, in many cases it may not even be all that accurate (i.e. Panama, West/East Berlin, Latin America 1950+).
Stay hungry, stay foolish!
