The question I ask myself like almost every day is: ‘Am I doing the most important thing I could be doing?' Unless I feel like I’m working on the most important problem that I can help with, then I’m not going to feel good about how I’m spending my time. And that’s what this company is.

If I were starting now I would do things very differently. I didn't know anything. In Silicon Valley, you get this feeling that you have to be out here. But it's not the only place to be. If I were starting now, I would have stayed in Boston. [Silicon Valley] is a little short-term focused and that bothers me.

I would only hire someone to work directly for me if I was willing to work for that person.

Our strategy is very horizontal. We're trying to build a social layer for everything. Basically we're trying to make it so that every app everywhere can be social whether it's on the web, or mobile, or other devices.

Building a mission and building a business go hand-in-hand. It is true that the primary thing that makes me excited about what we're doing is the mission, but I also think, from the very beginning, we've had this healthy understanding which is that we need to do both.

AI systems will enable doctors to diagnose diseases and treat people better, so blocking that progress is probably one of the worst things you can do for making the world better.

I don't have an alarm clock. If someone needs to wake me up, then I have my BlackBerry next to me.