Free publicity and word of mouth is probably the best and cheapest form of advertising. Learn to use it to your advantage.

I read a fair amount [of science fiction], and you know it was certainly inspirational. I have to pinch myself to think that we might be able to make some of [what I've read in science fiction books] come true.

I had no plans to be an entrepreneur. I just wanted to be a journalist and write for a magazine. At 15, I just decided to leave school and launch a national student magazine.

Give your employees a mission that matches their ambitions. When you challenge people, they surprise you.

The best advice I ever received? Simple: Have no regrets.

Fun is one of the most important - and underrated - ingredients in any successful venture. If you're not having fun, then it's probably time to call it quits and try something else.

Success cannot be measured in wealth, fame or power, but by whether you have made a positive difference for others.