Kevin O'Leary's mom taught him this important lesson about success (that he gave to his own kids too)

Kevin O'Leary: My mother gave me this advice — and now I pass it down to my...

Many moguls — like Richard Branson and Elon Musk — credit their mothers for teaching them early lessons that had a big impact on their success later in life.

Kevin O'Leary, star of ABC's "Shark Tank," is no exception, except in his case, the lesson came from his mom cutting him off financially.

"My mother was very influential in my career because she supported me from birth to last day of college," O'Leary tells CNBC Make It. "And then she said to me, 'After this, I'm done. My work is over. You got to make it on your own.'"

Kevin O'Leary
Courtesy of Kevin O'Leary

"She said to me, 'The dead bird under the nest never learned how to fly,'" O'Leary says. "I said, 'What's that mean, mom?' She said, 'It means no more checks.'

"I said, 'Mom, that's a great poem, but I need some cash here.' She said, 'No, no, no, no. I've done my work. Now you do yours.'

"And that was very important to me."

Being on his own forced O'Leary to hustle to achieve success: In 1986, O'Leary founded software company Softkey Software Products in his basement with no cash but a lot of hard work. He ultimately built that company into a huge business, later called The Learning Company, which he and his co-founders sold to the Mattel Toy Company for $4.2 billion in 1999.

The value of making it on your own is now something O'Leary now preaches too. 

O'Leary recalls that after he became successful, he asked his mom if he could pay her back for the financial support she had given him throughout high school and college.

"She said, 'No, I owed you that. And you should think about that for your children. Pass it on and pass it forward. But when they finish college, tell them the same thing — the dead bird under the nest never learned how to fly,'" O'Leary says.

"And that's exactly what I told my kids."

Indeed, O'Leary famously made his kids fly coach while he flew business class when they were growing up, and he cut them off financially after college.

"And [my kids] said the same thing to me: 'That sucks,'" O'Leary says. "But now they're off on their own, and they're figuring it out. And I'm so proud of what my mother taught me."

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

Kevin O'Leary: This is the job-hunting advice I gave to my daughter