Before Microsoft became a success in the 1980s, co-founder Bill Gates struggled with self-confidence and actually feared that his business would be a bust, he told students during a Q&A at Harvard last month. "Even the idea that Microsoft would be a big company, I never would admit that to myself," Gates said. Gates was an introvert, even, he has said, antisocial, and his original plan was to teach math. "When I was in high school I thought, 'Hey, I'm a good student and therefore I should go be like a professor of mathematics,'" Gates said. The academic discipline, Gates thought, also had "a certain purity to it," which he found alluring: Math problems, he said, "are the hardest problems to solve, and you know I like hard problems." Until his old friend and future business partner Paul Allen convinced him to seriously pursue computer programming, Gates wasn't planning for a career in tech or business. Instead, Allen challenged him to leave his comfort zone — in more ways than one.

Although Allen didn't go to Harvard with Gates, the two worked together as computer programmers at software company Honeywell in the summer of 1974, following Gates' freshman year. When the world's first personal computer kit came out later that year, Allen suggested Gates to try something different. "Oh, you think you're so smart, can you figure out this computer?" Gates recalled Allen telling him. "And I was like, 'Well, yes, I can.'" After seeing the first computer with a microprocessor in person in Harvard Square, they decided "it was time to drop out and go really build Microsoft to be the first in that business," Gates said. The decision required a serious mental shift. "So you know, that idea of being an academic to being a CEO, manager, leader type, that sort of developed over time," Gates said.

Paul Allen, from Asymetrix Corporation/Vulcan Inc., and Bill Gates, from Microsoft, share a laugh at the annual PC Forum, Phoenix, Arizona, February 22-25, 1987. (Photo by Ann E. Yow-Dyson/Getty Images) Ann E. Yow-Dyson | Getty Images