In a 2012 interview with Charlie Rose, Cuban was asked who the most impressive person he ever met was. The Dallas Mavericks owner said that it was his late father "for a lot of different reasons," but singled out a line from his dad that stuck with him.
"His best line to me always is, 'Today is the youngest you'll ever be, live like it,'" Cuban said. "So that's kind of like my motto."
Cuban learned the value of hard work from his father, Norton, who installed upholstery in cars to support their working-class family in Pittsburgh. while his mom worked a variety of odd jobs to help pay the bills.
In 2019, Cuban said on "The Dan Patrick Show" that he could still clearly picture the moment when he told his dad he had earned six figures for the first time.
"I remember telling my dad I made $100,000 in a year, and he cried," Cuban said at the time. "I don't think he ever made more than $40,000 in a year."
Cuban and his Broadcast.com co-founders would become billionaires in 1999 when they sold their company to Yahoo for $5.7 billion in stock.
But for Norton, his son's success didn't stop him from doing his job every day — he kept working on cars well into his 70s. Cuban's dad wouldn't even let him pick up the bill at restaurants when the two ate together.
"He was dad — and so if we went out to dinner, he was pulling out the credit card no matter what," Cuban told Patrick. "The minute I said, 'Dad,' he just looked at me with a death stare like, don't even think that you're going to pay for dinner."
It wasn't until Cuban bought the Dallas Mavericks in 2000 that he was finally able to convince his dad, who passed away in 2018, to stop working.
"I couldn't get him to retire," Cuban said on the show. Buying the NBA team, though, "was the impetus for him to retire and come down to Dallas and live and hang out and go to Mavs games. It was really special."
Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank."
Sign up now: Get smarter about your money and career with our weekly newsletter