My optimism and confidence come not from feeling I'm luckier than other mortals, and they sure don't come from visualizing victory. They're the result of a lifetime spent visualizing defeat and figuring out how to prevent it. Like most astronauts, I'm pretty sure that I can deal with what life throws at me because I've thought about what to do if things go wrong, as well as right. That's the power of negative thinking.

Spaceflight isn't just about doing experiments, it's about an extension of human culture.

Every single day you're the result of what you did on the days prior.

If you start thinking that only your biggest and shiniest moments count, you're setting yourself up to feel like a failure most of the time.

The emotional build-up and anticipation if you travel at Christmas can make it harder to enjoy a trip. I think sometimes it is better to travel outside of conventional holiday times for that reason.

Life off Earth is in two important respects not at all unworldly: you can choose to focus on the surprises and pleasures, or the frustrations. And you can choose to appreciate the smallest scraps of experience, the everyday moments, or to value only the grandest, most stirring ones.

I've been lucky enough to fly to space twice.