When billionaire entrepreneur and investor Mark Cuban started his first business, he decided to go all in. So all-in that he didn't take any time off for nearly a decade, he says.

"I didn't take a vacation for the next 7 years," Cuban told "The Playbook," a video series published by Sports Illustrated and Entrepreneur, in an episode that published on June 3. "All I did was learn, learn, learn."

Cuban launched his first startup, a software company called MicroSolutions, at age 24. At the time, he was sharing a three-bedroom apartment with six roommates and had just lost his job at a computer software store. The situation made it easy for him to find the drive to build a company, he said.

"I was broke as f---," said Cuban, 66. "I'd always been entrepreneurial, but that's motivating. I only had one direction to go, and I wasn't going backwards."

Cuban was so single-minded in his efforts to build his business that he refused to take any time off, he said. He never would've reached his current level of success — starring on ABC's "Shark Tank" for 14 years, owning a stake of the NBA's Dallas Mavericks since 2000 — if he'd attempted to have a work-life balance, he added.

In his view, his options were to either work on his business every day or let someone else beat him, he said: "There is no balance. If you want to work 9-to-5, you can have balance. If you want to crush the game, whatever game you're in, there's somebody working 24 hours a day to kick your ass."

Cuban has previously discussed his belief that a strong work ethic and willingness to put in the hours is the trait that is most likely to bring you success.

"The one thing in life you can control is your effort," Cuban said in June 2023, in a LinkedIn video post published by entrepreneur and venture capital investor Randall Kaplan. "And being willing to do so is a huge competitive advantage, because most people don't."

At age 32, Cuban sold MicroSolutions to CompuServe for $6 million. His next venture, audio streaming service Broadcast.com, sold to Yahoo in 1999 for $6 billion. His estimated net worth is now $5.7 billion, according to Forbes.

After becoming a newly-minted millionaire, Cuban took off his watch and threw it away, he said during a SXSW panel in March 2024. The gesture was symbolic, he noted: With millions in the bank, he wanted to reclaim his time rather than feel like he owed it to anyone else.

"I wanted to make enough money so I didn't have to respond to anybody else," Cuban said in a MasterClass course that published in February 2024. "I could make my own schedule and live my own life the way I wanted to do it."

Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank."

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