Even though running is physically straining, it's mentally refreshing. Especially when you feel like you've accomplished something.

There's a lot of social input when you put these things out there. People's ideas cross with other people's thoughts.

The most rewarding thing for me has been this affirmation for me that people are basically good and smart, and if you give them a simple tool that allows them to exhibit that behavior, they'll prove it to you every single day.

A personal belief is that if you're not personally invested in what you're working on, you'll fail.

I think of Twitter as a messaging system that you didn't know you needed until you had it. Think about when cell phones first started coming out. People said, "Why would I carry my phone around?" And now you'll drive back to your house thirty miles if you forget your cell phone.

The thing that excites me, and the thing that excited me about Twitter, is the idea of a flock of birds moving around an object in flight.

When you think of a social network, you have these two-way interactions: "Are you my friend? Yes? No? Yes?" Like LinkedIn, it's business oriented, but it's all about establishing connections. You connect to me through my other connections, and that sort of thing, and you sort of define who your friends are. Twitter doesn't have that.