Mark Cuban followed his friends to Dallas in 1981 after getting his bachelor's degree from Indiana University.

He remembers that when he first moved into their apartment, he didn't even have his own room. Things were so cramped that he'd come in at night after bartending and have to sleep on the couch or, if that was taken, the floor. He kept his few belongings in a heap.

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Cuban spent his 20s living cheaply and investing money in his first business, software distributor MicroSolutions. When he was 31, he sold the company to H&R Block for $6 million. The $2 million he personally made on the deal put him on the path to becoming the billionaire investor, entrepreneur, and Dallas Mavericks owner he is today.

In his book "How to Win at the Sport of Business," Cuban writes that if you're in your 20s, you don't need to share a gross apartment with a bunch of friends, but you should live cheaply, even if you happen to be doing well.

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Paying off bills, debt, and establishing a nest egg is far more important than indulging in a sprawling home or high-end fashion, he says.

"It doesn't matter where you live," Cuban writes. "It doesn't matter how you live. It doesn't matter what car you drive. It doesn't matter what kind of clothes you wear."

If you use your 20s to pay off student-loan debt, avoid credit-card debt, and build savings, you'll thank yourself later.

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"The more you stress over bills, the more difficult it is to focus on your goals," he says.

Whether you're using your 20s to build your own business or establish a rewarding career, "the cheaper you can live, the greater your options," Cuban writes.

This article originally appeared on Business Insider.

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