The strongest feelings I experienced were in Davis Cup. It was the most powerful thing: the victories and the losses. It hits you in a distinct way. It's another level of satisfaction - another level of sadness.
Sometimes we get very frustrated here on court. It is tough to control. It is a mistake.
I think one has to understand that there are stages in life, and that the life of an athlete has its limits. It's short, and then it stops, and sooner or later you have to accept that.
Sometimes the ATP puts a lot of pressure on the players and sometimes you get injured because you play on a dangerous surface. Nothing happens, no one pays for that.