I play tennis five hours a week, from Monday to Friday, for one hour every day. I like to be fit. If I can't exercise, I feel bad - I need to sweat and run to feel like I'm in good shape.
You never know how long Federer is going to play, but in my opinion he has at least one or two more grand slams to win. It depends how long he stays motivated. For me, he is the greatest player to ever play the game.
It's tough when you're No. 1. You don't have any private life, you can't even walk anywhere. I think that was one reason why I lost my motivation to play tennis.
As tennis players, we work and we sacrifice many things. To lose, that's not a happy thing - I mean sure, I was disappointed. You have to come back strong. But to win the last point in a grand slam tournament, that's the most beautiful and most satisfying feeling you can get as a tennis player. It's worth it.