You can train your mental strength just like you train your body. If your body looks fit or ripped, it looks strong, and you can flex your muscles. So, physically, you have a certain strength. Mentally, it's the same thing. You can train your psychological strength.

That's the most terrible mistake you can make: to relax. It's difficult to become a champion, but it's more difficult to maintain it for many years because you're getting too comfortable.

The first thing I learned in boxing is to not get hit. That's the art of boxing. Execute your opponent without getting hit. In sports school we were putting our hands behind our backs and having to defend ourselves with our shoulders, by rolling, by moving round the ring, moving out feet.

This guy [Tyson Fury] really wants to prove himself in the ring and confirm what he keeps telling everyone, that he's the best in the world.

I'm playing right now a role, and the role is called the 'Heavyweight Champion of the World.' And it takes all of the time. And I love this role, and it takes a lot of attention for me for the sport, and I just don't want to lose the title, so that's why I have to stay focused and not become an actor.

Mental strength is really important because you either win or lose in your mind. And I'm not solely talking about sporting matches, boxing events - anything you do, you do it first with your mental strength. And you can actually train and develop it, and I am responsible for what I'm saying because I have experience with that.

In Soviet times the border was closed so we couldn't get out of the country, and I had been reading Robinson Crusoe. I wanted to see the ocean, I wanted to see boats, I wanted to see black people, because we didn't have that in the Soviet Union. I was all excited by that stuff.