Sal Khan: The best advice I ever got

"Don't talk about stuff. Do it." Sal Khan and son.

FORTUNE -- "One of the powerful things Bill Gates told me is 'Learn to say no.' You don't have to make everyone happy. I've also learned by observing how deeply he goes into anything he cares about. How well he knew the nuances of my product was a huge signal that no manager should feel they're above the pay grade.

"But one piece of advice that's driven me the most came from a commencement speech by then-MIT president Charles Vest. He said to keep on moving. Cheesy, but it's amazing how true it is. Don't talk about stuff. Do it. When your organization is paused, and when the spirit of just seeing what happens dies, that's when you should be worried. Before I make a video for Khan Academy, I don't think, Let me go talk to some people and do focus groups. Obviously you have to have some learning, but if it's ruining the tempo of activity, you have to rethink things. At the end of the day, what matters is whether your product works and whether people like it."

Sal Khan

Age: 35

Job experience: Founder and executive director of the nonprofit Khan Academy, a virtual school providing software and 3,000-plus video tutorials in math, science, and other subjects. Most are taught by Khan, who conceived of the idea in an effort to tutor his cousins remotely. Former hedge fund manager; has three degrees from MIT and an MBA from Harvard.

Claim to fame: In November 2011, Khan Academy had 3.7 million unique visitors and 42 million page views; Bill Gates uses Khan's videos to help his three children with schoolwork. Khan Academy has since received donations from the Gates Foundation; it also won $2 million from Google in 2010.

This article is from the January 16, 2012 issue of Fortune.