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.

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

If you haven't learned to ride a bike by the time your peer group has, then suddenly it's an embarrassment and you'll avoid opportunities where you're expected to ride a bike. And then it starts shaping your behaviour. Reading is much subtler, but much more destructive if you have not - for whatever reason - learned to read by the time you should.

So without that Canadian invention we were grounded. And so that was a really important and key part of the mission and Canadians should take real pride in it.

Doing a space walk. It is one of the most rare human experiences. To leave your spaceship and go outside, so that you are alone in the universe with Earth distant and the universe around you. That is amazing.

The rough and ready improvisational quality to life on board the International Space Station is reminiscent of a long trip in a sailboat: privacy and fresh produce are in short supply, hygiene is basic, and a fair amount of the crew's time is spent just on maintaining and repairing the craft.

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.