Novak Djokovic is one of a kind and while others try to emulate him, they simply can't and for a very specific reason.
Each individual person on planet Earth is different. We're all different, starting from our body composition to our personality. Most of us fall within what's called 'average' but some of us are exceptional in different ways. Some excel at painting, and some excel at swinging racquets as simple as that looks.
Novak Djokovic is the latter as he's arguably the greatest tennis player who ever lived and for very good reason. He worked really hard for everything that he has but some of that came down to luck as well. His physical trainer, Marco Panichi, hails him as a genetic phenomenon per a recent interview.
There is more than one reason, but any consideration must start from the fact that Nole is genetically a phenomenon. He is someone capable of doing everything with simplicity and consistency, but also capable of doing things that others are prevented from doing.
Plenty of people have adopted some of the things Djokovic does with varying levels of success which shows that most of this is simply down to individuality.
Djokovic's physical prowess has certainly contributed to his greatness. Even Rafael Nadal admitted that Djokovic's ability to circumvent injuries has greatly helped him in his pursuit of being the greatest of all time. He's had the least amount of injuries by far but he's almost the most dedicated to avoiding that practising various disciplines from around the world.
Nole is a demanding champion, he wants a lot from himself and, consequently, those around him must adapt to these ambitions. And his motivation is always very high, he never suffers any downturn. We start training again on December 10, then he goes to Australia and starts the circuit again.