Everyone knows about the hard work Fed puts in for fitness, the workouts in Dubai etc. But all the top pros work on their fitness. If anything, Murray and Djoker have probably put in even more effort.
What makes Fed special is he's by far the most talented. His strokes don't cause any undue stress. The footwork allows him to be in position. He never grinds. The other big 3, and most top players, routinely play long grinding matches to win. Fed only does that when he's having a bad day. He's far more aggressive and has many more options, so he'll change strategies, conserve energy and find a way to win with less wear and tear on the body.
This is why he's been able to play at the top for so long, apart from the mental aspect.
What makes Fed special is he's by far the most talented. His strokes don't cause any undue stress. The footwork allows him to be in position. He never grinds. The other big 3, and most top players, routinely play long grinding matches to win. Fed only does that when he's having a bad day. He's far more aggressive and has many more options, so he'll change strategies, conserve energy and find a way to win with less wear and tear on the body.
This is why he's been able to play at the top for so long, apart from the mental aspect.