17 ways you should invest your time in your 20s for long-term success

There are a number of life skills people need to master, and your 20s is the time to start practicing. Without the pressure of parents or school to motivate you, you'll need to exercise discipline and motivate yourself to learn the essentials.

These skills can range from patience and dealing with rejection to living within your means and good table manners.

Francesco Wang refers to this as "life-extending" time.

"Investing time in caring for your health ... will certainly yield you more time, literally — in days, months, if not years tacked on to your life," he writes. "Yet we often take our health for granted until we experience a wake-up call."

Instead, he suggests proactively investing your time in your health by eating well, exercising regularly, getting plenty of sleep, regularly seeing your doctors, and taking care of your emotional, mental, and spiritual health.

Benjamin Franklin began and ended each day with a question: "What good shall I do this day?" in the morning, and "What good have I done this day?" in the evening.

In fact, many great thinkers embraced the idea of constantly questioning things.

As Albert Einstein reportedly said, "Learn from yesterday, live for today, hope for tomorrow. The important thing is not to stop questioning."

Of course, getting into the habit of self-reflection is easier said than done, as we often prefer to avoid asking ourselves the tough questions. As philosopher and psychologist John Dewey explained in his 1910 book, "How We Think," reflective thinking involves overcoming our predisposition to accept things at face value and the willingness to endure mental unrest.

But enduring this discomfort is well worth the effort, as it can result in the confidence boost necessary to perform better in our work and daily lives.

Questions to ask yourself could include Steve Jobs' "If today were the last day of my life, would I want to do what I am about to do today?" or Quora user Michael Hopkins' "How are you doing?" and Quora user Soham Banerjee's "Why so serious?"

"Fail," advises Arpit Sethi. "Out of our teens, this is the best thing that can contribute in the making of an adult. The more we fail, the more we learn."

You'll never have more energy or ability to think than when you're in your 20s, says Shulamit Widawsky, and you'll never be more vulnerable. This is the time to push your limits and recover from the failures that are inevitable when you take risks.

"Knowing what you can do and what you can recover from will make the whole rest of your life more successful," she says.

As the stresses of daily life become more burdensome in your 20s, it's important not to forget about taking care of your mental health.

Mehta suggests starting a mentally stimulating hobby like playing chess, role-playing games, or solving puzzles to keep your mind sharp. Hobbies can also be a good creative outlet or an exercise in relaxation.

Garv Suri recommends spending half an hour every day alone to get to know yourself better.

Tonya Turpin says that actively becoming aware of what's going on inside your head is the only way to truly understand yourself.

"You will never have this much energy, health this great, or this much disposable time again in your life," writes Heidi McDonald. "Make the most of it. This is your best chance to make a difference in the world."

Volunteering can also do wonders for your professional life, too. Donating your time can teach you a new skill, help add something special to your résumé, and you allow you to meet new connections with similar interests as you.

Wang cites the "Good Samaritan" study from Princeton University in 1973, which found that whether a person was in a hurry had a huge effect on if they'd stop to help an injured person. Only 10% of those in a hurry stopped to help an injured person, 45% of those in somewhat of a hurry stopped, and 63% of those not rushed at all stopped.

"This means that being in a rush may be preventing you from being the kind of person you want to be — the kind to stop and help someone in need," Wang says. "Building in lots of cushion time in your schedule and preventing 'constant hurriedness syndrome' is a great investment in yourself and in the quality of life of those around you."

The beauty of saving for your retirement in your 20s lies in compound interest, Allison says. Even if you open a retirement account today and put in $5 a month, "the effects of compound interest on that extra decade or two can literally mean the difference of hundreds of thousands of dollars more that you will have for your retirement."

Similarly, Tanmoy Roy suggests having fun but living frugally and allocating some money to pay off your debt on a monthly basis. You may not be saving for a home just yet, but down the road your student loans could prevent home ownership.

To find a meaningful cause, McDonald suggests keeping up with the latest current events by following the news.

"Chances are, you'll find your passion, whether that's a cause you're interested in or a niche you believe you can fill," she says.

Sanjay Kadel advises being wary about where you get your information. "Don't believe in whatever is there on the internet," he writes. "Do some research and then conclude whether it should be registered or eradicated."

"There is nothing that will help you more than reading," says Deepak Mehta.

He suggests a wide variety of books, from young-adult fiction and law to Dickens and Tzu, to learn more about contrasting viewpoints. "Do not be afraid of coming across a convincing viewpoint that is totally antithetical to yours," he says.

Reading is also a great way to exercise your mind, says Jereme Allison, because it activates almost all areas of it. "The mind is a muscle. If you don't use it, you lose it," he says.

"One great habit is a weekly review to look back at the past week and lay out the one coming up," says Curt Beavers.

He advises pondering:

1. What went well last week? (Celebrate and continue these.)

2. What didn't go well? (Stop, overcome, or remove these from your plate.)

3. Based on the answers above, what changes do I need to make to make this week better?

It doesn't matter how much you travel in your 20s, says Shrey Garg, but rather how you travel.

"Don't be a tourist, but a traveler. This will help increase your vision and make you realize how big and small the world is at the same time," he says.

The key, according to Allison, is experiencing new things: "Get to know that there is a bigger world out there. Learn about other cultures. Try new foods. You will be surprised at what you discover."

Mario Hari suggests traveling with complete strangers. "Experience the motley mindset of people. And if you study their emotions carefully, you will get an intuition about what every soul is searching for," he writes.

Whether you join a book club or head to the pub for karaoke or trivia night, Mehta says it's important to meet more people outside your friend circle and try to rid yourself of some of your social anxiety. It's important in your 20s to become more comfortable around others.

"I know after college one's social group often changes, so joining organizations helps one expand their circle of friends," Hunter McCord writes.

Growing your circle of loved ones and spending time with them is not something you will regret, he says. "I never heard of anyone at the end of their life wishing they spent less time with loved ones."

The fact that it has been a few years since you've set foot in a classroom doesn't mean you should stop learning.

And don't limit yourself to subjects that would have an obvious impact on your career. After dropping out of college, Steve Jobs still audited the occasional class, and one course he took on calligraphy was a huge influence on him and inspired "the wonderful typography" personal computers have today.

You'll likely never have more free time than when you're in your 20s, and using it to start a side hustle could give you the greatest return on investment.

"A side hustle is a business you run in your free time that allows you the flexibility to pursue what you're most interested in. It's a chance to delve into food, travel, fashion, or whatever you're passionate about whilst keeping your day job," writes Susie Moore, a writer and confidence coach.

She says the great thing about having a side job, apart from the extra income, is that it allows you to use talents that may remain dormant in your 9-to-5 job and make a meaningful impact by doing work that you love on your terms.

"People aspire to live a memorable life, and there's this tragic reality that most of us don't," Dustin Garis said last year during his TEDx talk.

For two years Garis traveled around the world, and on his journey he says he learned that "life is not the number of days you live; it's the number of days you remember."

The key to living a memorable life, he says, is pursuing one through breaking out of routine, incorporating change every day, and the "epic and everyday acts to save the day from being lost."