Mark Cuban's net worth? Reportedly it's $3.3 billion.

Before he became the most-beloved face on Shark Tank, Cuban had some cash to throw around. The owner of the Dallas Mavericks has made smart investments and made a cool few billion off his sale of in 1999.

But before he made his first $1 billion, Cuban had to make his first $1 million. In a recent interview with Money Magazine, he discusses the very book that helped him get there.

It's called How to Retire by the Age of 35, by Paul Terhorst. The book came out in 1988, and has an old-school typographic cover to prove it. Though many of the Amazon reviews claim some of the advice is outdated, it still contains plenty of food for thought. (And Cuban, like the book, still has some unconventional ideas regarding the future.)

Terhorst presents a straightforward strategy. Cut down your expenses and live frugally on much less than you earn. Invest the rest wisely. Steer clear of the items that typically represent the American Dream -- more house than you need, nicer car than is necessary. and eating fancy meals out. The book encouraged readers to live on $50 a day.

"The whole premise of the book was if you can save $1 million and live like a student, you would be a millionaire and you could retire," Cuban told Money Magazine. The secret to having enough money to retire early is to save as much of it as you can.

So as he was starting his career, that's what Cuban did. You might be surprised by some of the things the guy who's worth $3.3 billion at age 59 did in his 20s to pinch pennies: live with five roommates; eat macaroni and cheese; drive his beater car around looking at mansions he couldn't come close to affording at the time.

"I had a Fiat X1/9 with a hole in the floorboard. That was my decision. I was determined to save money and I was determined to be able to retire," he says. At the time, Cuban says he wasn't even doing it to be "super rich." He says he wanted to have money to travel, to have fun and to "party like a rock star."

Above all, Cuban told Money Magazine that reading How to Retire by the Age of 35 taught him to be disciplined with his money. That was the most important lesson of all as he grew from millionaire to billionaire. "I think it's possible to have a million dollars in the bank even if you're not an entrepreneur," he says. "There are a lot of strategies for people who work their way up the corporate ladder, or even bounce from job to job."

And you need to be smart and strategic with how you spend your money.

It could be making smart investments in companies that went on to be successful, like he has. Or, you might consider making a smart investment in your education -- "whatever it may be," Cuban says, "to help you get to the point where you can truly save money." ​