Ultimately, leadership is not about glorious crowning acts. It's about keeping your team focused on a goal and motivated to do their best to achieve it, especially when the stakes are high and the consequences really matter. It is about laying the groundwork for others' success, and then standing back and letting them shine.

The beauty of the space station, and of human spaceflight, is that it is now at a level of maturity where you can invite people on-board, which is what I worked so hard to do on social media and all the videos I made.

A lot of people live in fear because they haven't figured out how you're going to react when faced with a certain set of circumstances. I've come to terms with this by looking deeply into whatever makes me fearful - what are the key elements that get the hairs up on the back of my neck - and then figuring out what I can do about it.

You should have a fear of some things. That doesn't mean it incapacitates you from your ability to figure out a way to deal with it.

The communities and countries best at using energy to optimize a microclimate for human life are also the ones whose people have the longest average lifespans. Canada, Sweden, and Iceland - places with inhospitable winter weather - are frontrunners in sustaining human health and life.

And then finally, I'm the commander, so I am fundamentally responsible for the lives of the other people on board and the health and longevity of the space station. I need to bring six people back happy, healthy and feeling like they've had the best six months of their life.

I think there are lots of ways to exercise ambition and accomplish things using leadership without going into elected politics. So, categorically, I have no intention of going into elected politics. None.

The world, when you look at it, it just can't be random. I mean, it's so different than the vast emptiness that is everything else, and even all the other planets we've seen, at least in our solar system, none of them even remotely resemble the precious life-giving nature of our own planet.

I've had a chance to see something that is way outside everybody else's frame of reference and gives a perspective that is very different from everyone else's.

For the last several years and culminating in six months in orbit next year, I've been training for my third space flight. This one is almost in a category completely different than the previous two, specifically to live in on the space station for six months, to command a space ship and to fly a new rocket ship.

If you don't like airline food, you'll probably have the same impression of space station food. I would not fly to space for the food.

Almost everything worthwhile carries with it some sort of risk, whether it's starting a new business, whether it's leaving home, whether it's getting married, or whether it's flying in space.

The International Space Station is a phenomenal laboratory, an unparalleled test bed for new invention and discovery. Yet I often thought, while silently gazing out the window at Earth, that the actual legacy of humanity's attempts to step into space will be a better understanding of our current planet and how to take care of it.

There are no wishy-washy astronauts. You don't get up there by being uncaring and blase. And whatever gave you the sense of tenacity and purpose to get that far in life is absolutely reaffirmed and deepened by the experience itself.

When you're on one of the Caribbean islands, sometimes it's hard to picture how they fit in with the rest, but when you see them all joined together like a necklace from space, you see the natural geographic connectedness of them all.

It was remarkable to see from space how predictable people are. Our homes and towns are almost all in places with moderate temperatures, and they generally have the same shape - a thinly occupied outer blob of suburb surrounding a densely populated core, all based around a ready source of water.

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

As an astronaut, especially during launch, half of the risk of a six-month flight is in the first nine minutes.

It is spectacular. From about five minutes in, when we knew for sure that we were going to have the weather to go, the smile on my face just got bigger and bigger, and I was just beaming through the whole launch. I mean, it is just an amazing ride.