Albert Bourla went from Greek veterinarian to the CEO of the company making the world’s most-used vaccine, Pfizer.

“The essence of all of these very big, very risky, very aggressive, very ambitious projects, is that you need to believe. If you let the doubt occupy your brain cells, it’ll replicate faster than the virus. You need to constantly believe that it can be done.”

Bethenny Frankel is all about hustle. While you may know her as a Real Housewife, this inspirational renaissance woman pulled herself out of poverty to become the mogul she is today. How did she strike gold with her beloved SkinnyGirl brand?

“I don’t see age, I don’t see color, I don’t see gender. I wouldn’t have gone into the liquor business if I saw gender. It’s a man’s business. All men. I didn’t even notice that they were men saying no to me.”

Brian Chesky, the founder and CEO of Airbnb, says his success is a reminder of the kindness in the hearts of humanity, that his business plan relies on generous spirits. How did he go from broke to billionaire in a heartbeat?

“What they don’t teach you in Harvard Business School is that almost all entrepreneurs that were successful knew almost nothing when they started. … It’s jumping off a cliff and assembling the airplane on the way down, but you have no manual. So it’s basically: Can you learn really quickly?”