'Shark Tank' star Kevin O'Leary's secret to success: Don't focus on money

Kevin O'Leary, a star of ABC's "Shark Tank," is certainly qualified to dish out entrepreneurial advice. With the show in its tenth season, he's counseled hundreds of aspiring and established entrepreneurs.

He's also a wildly successful entrepreneur in his own right. In 1986, O'Leary started Softkey Software Products, which was later re-named The Learning Company, in his basement with no cash. He ultimately grew Softkey into a huge operation and, along with his nine other co-founders, sold it for $4.2 billion to the Mattel Toy Company in 1999.

Along the way, O'Leary learned a key lesson that he now passes on to every entrepreneur: Don't focus on money. Focus on freedom.

O'Leary recalls the day after he sold his company: He and his co-founders were suddenly wildly wealthy. One might expect a newly minted multimillionaire to buy a yacht or jet-set around the world for awhile. Not O'Leary.

"What do we do? We're right back to work. We don't know anything else," O'Leary says.

Starting your own business is "a journey," he explains. It sometimes ends up with liquidity, which helps you build personal freedom — and that's what you should focus on. "I don't need more money," he adds. "I just want to do the things in my life that I want to do, and money allows me to do that."

"I tell every entrepreneur," O'Leary says: "Don't focus on the cash. It's nothing about greed. It's all about personal freedom."

While the massive fortunes of icons like Jeff Bezos and Richard Branson might seem reason enough to become your own boss, that's not really what the field is about, O'Leary argues.

"You don't do entrepreneurship for the greed of money," he says. "Because what does it mean to be wealthy in America? [It means] you're personally free. That's what's important."

Growing up, O'Leary was passionate about photography; he even wanted to do it as a full-time career. But, due to the competitive nature of the photography profession, his father recommended that O'Leary learn how to run a business first. So O'Leary went on to earn his MBA from Ivey Business School at Western University, and then pursued entrepreneurship. Now, he says, his success in business has given him the freedom to return to photography.

"Now, because of personal freedom I have a massive collection of cameras from Leicas to Nikons and Canons and every lens they make," O'Leary says. "In a way, it's a full circle. I've gotten to do what I wanted to because I was successful in something else, and that's the great thing about entrepreneurship — you can pursue your dreams."

Indeed, many successful entrepreneurs have preached the importance of not focusing on money as the end game. Virgin Group founder and billionaire Richard Branson says that true success is not measured by how wealthy you are, but how happy you are. Meanwhile, billionaire Warren Buffett says he measures success by how many people love him.

"The pursuit towards success is to be personally free," O'Leary says, "to provide for your family and to be able to do the things you want to do with your life. That's a great gift of entrepreneurship."

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