A woman who has coached hundreds of millionaires and billionaires shares the secret to their success

Executive leadership coach Lolly Daskal has worked with hundreds of millionaires and billionaires.

The secret to their success doesn't boil down to one specific habit, routine or personality trait, she tells CNBC: "The secret of the true billionaire is what's going on on the inside."

In other words, the secret to success starts with your own psychology — not the specific actions you take. Daskal says that you have to know who you are and what you want, and you have to constantly challenge those notions, before you can even begin to influence others.

"There's so much literature out there about how to succeed," she says. "Most of the books talk about 'how': Do this and you will be that. But it doesn't work that way. We have it backwards. What we really need to do is to figure out who we are on the inside. We need to identify ourselves and say, 'I am a person that will do this.'

"Once you know that, then you know the thoughts you need to think; then you know the actions you need to take; then you know the values and the virtues you need to bring. But before you can do all the doing, you really have to concentrate on who you are being."

By understanding who you are, you can then start to recognize "when there are gaps in who you are and what you know," Daskal writes in her book "The Leadership Gap." And that can be helpful. "As a leader, you must get comfortable with the act of questioning yourself. When you stop questioning, you stop learning. And when you stop learning, you stop leading."

What separates the wealthiest, most successful people from the average person is that they "have the ability to rethink who they are," she writes. "They are open to learning, changing, and growing as leaders."

Ultimately, "if you want to have the mindset and the insight of a billionaire," she tells CNBC, "you have to figure out the who."

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