Well, yes, no, I certainly visualise … it was really … I had to have a very good idea of the geometry – that was crucial. Spacetime geometry so it's not three dimensions, you have to think of the whole four dimensional spacetime, and I get sort of used to thinking about four dimensions and using various tricks to get the picture properly. I do most of my thinking in visual terms, and I'm a very visual thinker rather than writing down equations.

I want my readers to laugh sometimes. Many readers in Japan read my books on the train while commuting. The average salaryman spends two hours a day commuting and he spends those hours reading. That’s why my big books are printed in two volumes: They would be too heavy in one. Some people write me letters, complaining that they laugh when they read my books on the train! It’s very embarrassing for them. Those are the letters I like most. I know they are laughing, reading my books; that’s good. I like to make people laugh every ten pages.

I’ve done almost 4,000 operations for brain tumors. I’m thinking of what’s going to happen ten or 12 steps before. I’m anticipating what’s going to happen in the operation, and I’m comfortable with where we are.

When I have a lot of pain, I try to confuse my mind to forget about the pain and think about the distance. I don't want pain to be in my mind, because I'd really lose focus on running. After winning, you won't have that pain, but it comes later. The marathon is hard; the second day, you don't go up or down stairs.

Max Levy, a German sprint cyclist who came second behind me a lot.

I don't enjoy it but I know that I have got to live with [myself] if I'm not going to give it 100 per cent. The key thing is getting to the start line and knowing that I couldn't have done any more, that I didn't back off. You accept the pain, because if you didn't there would always be that element of doubt.

The real problem is that the pain actually gets worse. You have created massive acidosis in your muscles so there is a huge quantity of hydrogen ions and the pH in your blood changes. For 15 minutes you lie there thinking, "God, this is really bad. I'm going to die. It has never been this bad before." And every time you think exactly the same thing. You have to lie to yourself by saying you're not doing a second set. Then, without moving for 15 minutes, almost to the second, I would roll over and think, "OK, I think I can do a second set now." During those sessions I have never felt more alive or so close to death.

Delivering papers in the freezing cold for my granny. I got paid in Panini football stickers, so it wasn’t all bad.

The six Olympic gold medals, because at school I was never great at sport. When I look back on my career I think, how on Earth did that happen?

A road track car, a Porsche GT3. I’ve done the 24-hour race in Le Mans, which was a dream come true.