they are all working hard on their fitness.
nole has simply taken his fitness as high as it is possible to take.
he borrowed chapters from muster and rafa books. he realized he could dominate the planet if he became an ironman.
Federer is doing great as well. he is about to turn 34.
Ferru is 33. only god knows how old Melzer is.
Tommy Haas has to be pushing 38 by now.
and then look at the Bryan brothers.
all these players figured out that they can compete for as long as they wish if they keep themselves supremely fit.