Warren Buffett is one of wealthiest people in the world, with a net-worth of just over $72 billion. When he gives advice on investment, people tend to listen. So what is the number one thing Warren Buffet believes you should invest in?

The answer: you.

As Buffett puts it, “Invest in as much of yourself as you can, you are your own biggest asset by far.”

But what does that mean? Aren’t we all invested, inherently, in ourselves? According to Buffet, it comes down to a few important aspects.

Look after the wellbeing of your body and mind.

“You only get one mind and one body. And it’s got to last a lifetime. Now, it’s very easy to let them ride for many years. But if you don’t take care of that mind and that body, they’ll be a wreck forty years later, just like the car would be.” — Warren Buffett

Both your body and mind require regular maintenance. You need to challenge them when they’re getting lazy and take care of them when they’re feeling under the weather. You need to give them the nutrients and sleep they need to function, and you need to see a doctor when they seem to be out of whack.

For your body: make sure you get regular exercise. The Department of Health and Human Services recommends at least 150 minutes a week of moderate aerobic activity or 75 minutes a week of vigorous aerobic activity. Or you can do a combination of moderate and vigorous activity.

For your mind: make sure you stay sharp, even as you age. Studies have shown that you can help prevent cognitive decline and reduce the risk of dementia with a few basic good health habits like staying physically active, getting enough sleep, not smoking, having good social connections, limiting alcohol to one drink a day, and eating a balanced diet low in saturated and trans fats. If you have certain health conditions that can impair cognitive skills (including diabetes, high blood pressure, sleep apnea, depression, hypothyroidism, and high LDL cholesterol), you can help protect your memory by following your doctor’s advice carefully.

Cultivate positive habits and daily routines.

“Chains of habit are too light to be felt until they are too heavy to be broken.” — Warren Buffett

It’s never too late to create a good habit or change a bad one. Nurturing the right habits – whether that’s going for a walk every day or sitting up straight at your desk – at first seems tedious, but with repetition becomes automatic. Choose positive behaviors that you can leverage to move your life and career in the direction you want.

Trying to change every bad habit you have or introduce a bunch of good ones all at once won’t work, so start small. Pick one habit you can start doing today, and do it: today, tomorrow, etc.

Never stop learning.

The Vice Chairman of Buffett’s Berkshire Hathaway Corporation, Charlie Munger, once said this about his colleague:

“Warren Buffett has become one hell of a lot better investor since the day I met him, and so have I. If we had been frozen at any given stage, with the knowledge we had, the record would have been much worse than it is. So the game is to keep learning, and I don’t think people are going to keep learning who don’t like the learning process.”

Just because school is over doesn’t mean you shouldn’t be constantly challenging yourself to learn more about the things you’re passionate about and the industry you’re in. Attend conferences, take online courses, set up time to talk with people you admire, find and/or be a mentor, and don’t forget to read.

Surround yourself with excellence.

“It’s better to hang out with people better than you. Pick out associates whose behavior is better than yours and you’ll drift in that direction.” — Warren Buffett

Who you spend time with influences the person you become, whether that’s by providing opportunities you otherwise wouldn’t have or by holding you back from something you would otherwise pursue. Be selective about who you put your time and energy into because it has the potential to come back, in positive and negative ways, to you.

Whenever you’re meeting new people, ask yourself: Are they making you a better person? Do they support your dreams and goals? Do you feel better when they’re around? If the answer is no to the majority of these questions, it might be worth considering putting a little distance between you and that relationship.

This is easier said than done, especially when it comes to family members or coworkers, but you have to mitigate negativity in your life or it will have the power to bring you down with it.

Spend time getting to know yourself.

“I insist on a lot of time being spent, almost every day, to just sit and think. That is very uncommon in American business. I read and think. So I do more reading and thinking, and make less impulse decisions than most people in business. I do it because I like this kind of life.” — Warren Buffett

If you want to get to the end of life and truly be happy with how you’ve spent your time, it’s important that you know yourself in a deep and meaningful way, first. Ask yourself questions, get to know yourself through journaling, try new things with an open mind and see what your reaction is. Unless you really know what and why things make you tick, it’s going to be hard to push yourself to be the best version of who you can be.

Do what you love to do.

“There comes a time when you ought to start doing what you want. Take a job that you love. You will jump out of bed in the morning. I think you are out of your mind if you keep taking jobs that you don’t like because you think it will look good on your resume. Isn’t that a little like saving up sex for your old age?” — Warren Buffett

It’s important to be aware of your own financial responsibilities, family obligations, and the realities that come along with the logistics of day-to-day life, but it’s equally as important not to waste the time you are given here because you will never get that back. You get one life. Spend as much of it as you can doing things that you love.

If you follow Warren Buffett’s advice and invest in yourself starting right now, you will see positive returns. And if there’s one thing in this life that you shouldn’t doubt, it’s investment advice from Warren Buffett.