Kevin O'Leary Says This Is the One Skill He Looks For in a Leader — But It's 'Almost Impossible to Find'

"Shark Tank" star Kevin O'Leary's new company, WonderAds , wants to disrupt the industry by making television advertising accessible to small businesses.

But when launching a new business, ensuring the company has an "effective" leader is one of the most important decisions a business owner will make, O'Leary says.

Related: Kevin O'Leary Launches AI TV Advertising Platform, WonderAds

"The difference between effective managers and ineffective managers is very simple," O'Leary tells Entrepreneur . "It's the ability to focus and determine the signal versus the noise. Whatever the business plan looks like today, particularly on a startup, I guarantee you, it won't be what it looks like in 24 months."

O'Leary says the ability to execute is paramount — and hard to find.

"Ideas are a dime a dozen," O'Leary said. "[But] execution skills are almost impossible to find. When you find executional skills, you can put that person into almost any business and achieve success."

O'Leary says top execution skills include being able to pivot, focus, and listen. He also stressed that the ability to waive off naysayers and negative opinions is an important part of being a leader.

"The naysayers, they don't matter," he says. "They're completely irrelevant."

Related: Kevin O'Leary: Job Hopping Can Be a Resume 'Huge Red Flag'

Want to work for O'Leary? Get some thick skin. True leaders don't care what you think about them, he says.

"If you're a manager, and you're concerned about what people are saying about you, think about you, or feel about you, you're completely wasting your time, you will never make everybody happy," O'Leary says. "It doesn't matter to me whether you like me or you don't like me, I don't care."