To have created one of the most respected companies in the world. Not necessarily the biggest.

I've used the Phoenix Centrifuge to replicate what the body's going to go through on the flight up. I've also done some gravity tests with ZERO-G [a charter-flight service in Arlington, Va., that uses modified Boeing 727s to simulate weightlessness], which went great.

I think entrepreneurship is our natural state--a big adult word that probably boils down to something much more obvious like playfulness.

I was the kind of entrepreneur that never really felt I made it. When Mike Olefield's "Tubular Bells" [Virgin Records' first release] sold 8 or 10 million copies, I suppose, at age 19, I could've possibly retired on the money. Instead, I immediately pushed the boat and took that risk again.

It's obviously incredibly important to keep the body fit in order to keep the mind fit, and be able to find time for friends.

I think in life the key thing is just to fight really hard to make sure something survives. If it looks like you've done everything you can to avoid failure, just move forward, move on and learn from it.

I moved into a nice houseboat in Little Venice when I was 15 years old. I found a girlfriend called Monday and a houseboat called Friday, so I had the week sewn up.