David Rubenstein

The 58-year-old financier is a co-founder of the Carlyle Group, whose $71 billion under management makes it one of the world's largest private equity firms. Carlyle has investments in more than 500 companies that employ more than 100,000 people.

Since I did not come from a wealthy family, becoming a professional was important to me. I went to law school, got a job at a firm, and learned that law wasn't really the profession it appeared. I wasn't a great lawyer, and I didn't have a passion for it. I read about Bill Simon, who bought a company with almost no money. He put under $1 million into Gibson Greetings, and within a few months it was worth $60 million. I said, "Hey, I like that business." I got a call from a friend who said, "I just quit my job at Marriott (MAR) this afternoon. Let's start an investment firm." Luck is important. Had I not met him, I'd still be practicing law.

I just got back from an around-the-world trip, which I do four or five times a year. I meet with companies we might invest in, people we are trying to recruit, and employees who want to talk to me. Private equity firms are in a race to build global franchises that people will recognize and put money in.

If you go back through the history of capitalism, the rule of thumb is that people who are very smart, focused, and have their own money at risk generally make more than people who are not. I don't feel like I've worked a day in my life. If you're going to be a success in life, you have to love what you're doing. I have a theory—which doctors don't agree with—that I've never missed a day of work because my immune system doesn't have a chance to absorb germs. Something happens when people retire: They drop dead of heart attacks. I read four to six books a week, 10 newspapers a day. For me, that's pleasure. This year I took my son to the Galápagos Islands and Peru. A BlackBerry works at the top of Machu Picchu, that much I can tell you.