30 life-changing secrets to success we wish someone had told us by 30

Life

If you don't make mistakes in your 20s? Then you're probably not doing it right.

In fact, some lessons you really must learn the hard way.

Next time you mess up at work, for example, don't be too hard on yourself. Instead, embrace the foible as an opportunity to learn — and to own your mistake, as self-made millionaire and financial guru Sallie Krawcheck suggests.

"Nobody cares about [the error] as much as you do," Krawcheck said: Everyone else is busy worrying about their own stuff. So take responsibility, then move on. Bouncing back is a skill that takes practice, after all.

But what about those career, financial and life mistakes that are worth avoiding? Or those lessons you'd simply prefer not to learn the hard way?

Mic polled staffers over age 30 and dug deep into career advice on what older professionals most regretted not knowing — or appreciating — in their 20s.

One big takeaway: The most debilitating mistakes aren't always the most memorable (or traumatizing) ones, like that time you let your debit card out of your sight, it was skimmed and a thief drained your bank account.

The really regrettable errors, instead, were the slow-burn bad habits and failings that evolved into chronic problems.

The real stuff.

So, in that spirit, here's a roadmap to doing better than most, and preventing your own too-real post-30 regrets.

These wisdoms will help save your money, time and relationships — leaving you wealthier, healthier and happier.

Winners play the financial long game

Broadly speaking, planning ahead and staying informed on basic, timeless principles will help you manage your cash — and turn it into wealth.

1. You "need" only one credit card. Plastic helps you build credit history. But don't sign up for every new card that comes along, trying to chase points and miles. And, whichever one you pick, pay off the entire amount every month.  

2. Knowing your credit score today will help you tomorrow. This measure of how well you use credit may seem unimportant now (when it is easy to mess up with late payments) but it'll matter a lot when actually need it — to buy a car or house or to secure a loan. Do a favor to your future self and find out where you stand today: That will help you correct course if necessary.

3. Paying more — even a wee bit more — above your minimum monthly debt payments is one of the best choices you'll make. An extra $50 a month may seem tough, but it makes a big difference in how quickly you'll pay off money owed and total interest. Plus, extra payments can boost your credit score.

4. Never buy a new car. Buy used, and let others take the bulk of depreciation.

5. Investing is your friend. Saving for retirement sounds like a drag, but you've gotta do it. Luckily, you'd be surprised how much it pays off: If you invest just a little money regularly in your 20s, you could have $1 million more dollars by the time you retire than if you wait until your 30s. So brush up — and jump in.

6. Roommates are a good investment. Obviously, roomies can come with  downsides. But you save a bunch of money. Plus, sharing space prepares you for marriage or partnership, by making you practice humility and compromise.

7. Expect the best, but prepare for the worst. Don't waste your time stressing about money. But do take the time to set up an emergency savings account.

Career wizards keep it simple

You can accomplish a lot — and even turn a gig into a calling — if you follow two no-brainer principles: Do your best and trust yourself. The rest will follow.

8. Finish what is in front of you before launching your grand plan. You have your whole life to figure out, well, your whole life. If you're overwhelmed or lost, focus on completing your current work project or — if you're still in school — getting that bachelor's (or master's) degree that you started. Baby steps.

9. There is no better way to impress an employer than working hard. It also is one of the best ways to earn, ask for, and then get a raise.

10. The best deal you'll get at any job is the one you get coming in the door — so negotiate going in. You may be delighted just to have the job. But you'll do yourself a disservice if you don't bargain now. So, assuming you have good reasons prepared, always negotiate your starting salary and title. It otherwise might be harder to make major moves later on.

11. The path to a successful career is rarely linear. Expect setbacks. And know it's okay to first quit the wrong job in order to find the right one.

12. Trust your gut. Even if you aren't thrilled with your work-life balance or salary initially, if you do love a certain industry, just start gaining experience. In other words, first make sure you are climbing the right ladder — then climb.

13. Come in early every day. The best productivity hack is the simplest. You will have plenty of quiet to get work done — and you'll build good will with your employer. Plus, if you work for yourself, early in means early done.

14. Never be afraid to say, "I don't get it." People generally love explaining things, because it makes them feel smart. If you ask someone how something works, you might be surprised by how willing they are to share.

15. The job world is made for "orderly" people — recognize if you aren't one. Call them Type A or overachievers (or, as Gretchen Rubin says, "upholders"): These people are on time, neat, detail-oriented, on-the-ball initiative-takers. In other words, that can't possibly describe everyone. So if that is not you, know that it is OK! Just be real with yourself. You might need to adapt to fit your square self in the round hole of expectations... or you might simply leave the round hole behind — to find or create a square hole of your very own.

People should always come first

More important than your career moves or financial decisions are your relationships with the VIPs in your life — and the time you make for them — that will determine how "successful" you are in the end.

16. Communication will set you free. There's a time and place for everything, of course, but avoid sitting on problems for fear of conflict. Get past the icky anxiety, and you'll find (sober) conversation is a powerful and effective change agent, whether the person in need of change is them — or you.

17. Embrace difference. If you don't have diversity in your friend group or at work, you might be missing crucial perspectives. Groupthink is bad for business, while heterogenous groups tend to be more successful. People who differ in age, race, sex, gender, sexuality, ethnicity, religion, and even outlook — optimists versus pessimists, for example — can enrich one another's lives.

18. Keep up with your network: IRL. Social networks are fun and can even be a boon to your career, but remember your most valuable assets are the people you actually know: in real life. Maintain these friendships through phone calls and in person, and you may discover your connections are the best path to the best jobs and — maybe — the best romantic partners.

19. But don’t waste time on people you are lukewarm about. Life is too short to put up with a selfish boo, a fair-weather friend or a bad boss. Just like money, time should be spent only on those who deserve it.

20. Talk big-picture money stuff with your partner early on. Don’t waste time worrying about the little things like your grocery budget for the week until you both agree on what is top priority long term. Discuss the biggies first: Do you want to live in a rural or urban area? Do you want to own or rent a home? Do you want to retire early? Do you want awesome experiences? Or kids?  The grander plan will inform how you end up spending money day to day.

21. Go ahead and go to bed angry. Cooler heads will prevail in the morning.

Health means wealth and so much more

You've got only one body. Don't sacrifice it at the altar of success.

22. Trick yourself into exercise. Some people go running every day like it ain't no thing. The rest of us mortals need carrots and sticks, like getting to watch a fun movie while climbing the StairMaster, or putting on gym clothes as soon as you're up on Saturday — so you feel guilty if you don't go. Or booking a class that'll charge you if you no-show. Or scheduling a beach vacation. Another carrot? People who work out tend to earn more money.

23. Buy insurance and go to the doctor — and dentist. Health insurance is a downer, it is hard to figure out and can be expensive. But medical debt is one of the biggest drivers of bankruptcy and insolvency. It's hard to recover, even after you feel better. So buy that insurance and get that preventative care. Better to pay a little bit monthly than a whole lot when you least expect it.

24. Everything in moderation, including moderation. Be realistic. Gulping down sugar is a bad idea, but so is crash dieting. The best, most sustainable diet might be less "healthy" and more "healthy-ish."

25. Yet "just one more" is never just one more. That goes for cigarettes, drugs, other abusable substances — and yes, even junk food. If you know you need to stop, quit today. Stop pretending like it'll magically happen tomorrow.

26. If you do nothing else, learn to cook. It will save you money — and make you far more mindful of what you're putting in your body.

27. Spend time in nature. Evidence abounds that it improves mental health.

28. Wear sunscreen. You'll thank us later. And you might even be able to use pre-tax money to buy it.

The only person who decides if you're successful is you

No, this is not just another way of saying "work hard." The truth is that life is a not a sprint against other people. It's a marathon against yourself, and you are the only one keeping track of your own time.

29. "Satisficers" know what's up. Maximizers are perfectionists who agonize over every decision. Satisficers figure out the acceptable minimum — and accomplish it. You can imagine which type of person ends up happier.

30. You can't buy happiness. But you can make the most of what money you've got by buffering against catastrophes that would cause unhappiness — and by spending in ways that enable happy memories (hello, vacation!).

Finally, remember: Lists like this one don't have all the answers.

They are just a starting point. So embrace your idiosyncrasies, find your own metric, and stop comparing yourself to your peers. Focus instead on goals with serious shelf life — that will still have meaning when you're 90.

Sign up for The Payoff — your weekly crash course on how to live your best financial life. Additionally, for all your burning money questions, check out Mic’s creditsavings, career, investing and health care hubs for more information — that pays off.