"What advice would you give to a smart, driven college student about to enter the "real world"? What advice should they ignore? I thought about this a lot when I gave the commencement address at MIT back in 2013. I said that if I had a cheat sheet I could give myself at 22, it would have three things on it: a tennis ball, a circle, and the number 30,000. The tennis ball is about finding something that you can become obsessed with, like my childhood dog who would go crazy whenever anyone threw a ball for her. The most successful people I know are all obsessed with solving a problem that really matters to them. The circle refers to the idea that you're the average of your five closest friends. Make sure to put yourself in an environment that pulls the best out of you. And the last is the number 30,000. When I was 24, I came across a website that says most people live for about 30,000 days--and I was shocked to find that I was already 8,000 days down. So you have to make every day count. I'd give the same advice today, but I would clarify that it's not just about passion or following your dreams. Make sure the problem you become obsessed with is one that needs solving and is one where your contribution can make a difference. As Y Combinator says, "Make something people want."