My running ambition is to keep doing it until I'm way past the point where I have any business running. Just to keep doing it throughout my whole life—to stay fit and feel good.

The current market cost for a space flight, about a week in space and about six people have gone with the Russians so far to the International Space Station; it costs about $30 to $35 million. So, it's not for the faint of heart. But our own market studies that we've commissioned as well as some public market studies all indicate that there are somewhere around 20 or so individuals every year who have both the means and the interest to do this. So, the market is definitely out there.

The expense of getting into space is the rocket launch, the rocket itself. Rocket's right now, commercial rockets cost probably somewhere between $50, or $120, or $150 million per launch. And those are all expendable. That is, you've got to buy a new rocket for each launch. So, that really is the critical part. If there was some kind of really, a revolutionary breakthrough and the price of rockets fell by an order of magnitude, I mean, just imagine what that would do as far as getting access to more ordinary people.

One of the things, and the most exciting, actually definitely the most exciting thing is, having children. You know, I didn't have children before. I had been married only a year before my space station mission, so having three-year-olds is a whole new experience and that's the new adventure. It may sound funny because people have kids every day, but having your own kids, having my own kids, was as fundamentally, or maybe even more fundamentally life changing then even flying in space.

I loved flying as much as I thought I would and continue to fly aircraft.

I attended a big human space flight conference in Beijing and I was going as myself. And really, there weren't any NASA astronauts there, I was the only so-called American Astronaut there. We had astronauts from most of the other countries, certainly from Russia, from France, from Japan, several other countries, but it was a little bit odd because here we are at an international gathering of a lot of astronauts and I'm talking about somewhere upwards of 30 or so astronauts, and I'm the only American. And I wasn't even there in an official capacity.

The space station mission was kind of the culmination of all of my experience of being a NASA Astronaut, so it had brought all of my previous experience into play. I had to learn the Russian language to a fluent level so that I could function as the co-pilot of the Soyuz Spacecraft that we flew up and back from the space station. And then the challenge of being the Commander of the whole expedition, a six and a-half month flight aboard the international space station. I felt the burden of the whole mission on my shoulders, which was fine, and fortunately everything did go well.