Houston has been making his days count practically since toddlerhood. When I was 24, I came across this website that says most people live for about 30,000 days. The circle is really about the idea that you’re the average of your five closest friends, so make sure to put yourself in an environment that pulls the best out of you. I use the tennis ball for that idea because of my dog, who gets this crazy, obsessed look on her face when you throw the ball for her. The most successful people and successful entrepreneurs I know are all obsessed with solving a problem that really matters to them. The tennis ball is about finding the thing you’re obsessed with. Three simple things, each of which symbolize important concepts to the 33-year-old. commencement speech, in which he revealed to the graduates that he would give his 22-year-old self a cheat sheet with three things drawn on it: a tennis ball, a circle and the number 30,000. In an interview with the New York Times, he brought up his 2013 M.I.T. If you could go back in time and talk to early-career you, what would you tell yourself? Quit racking up credit card debt? Get out of that bad relationship and focus on chasing your dreams? Dropbox CEO Drew Houston knows exactly what he would say.

Ceo of drop box