It's mostly genetics, you're born with a lot of "good raw material" to work with during training, for instance: Lance A., Ulrich, Marco Pantani, etc, etc.
Some people erroneously think that training alone would take them to the top, I've met many like that: "oh, if I could only have the time to train like them, I'd be the best"

It's like if I was trying to get the body of Arnold Swarchezneger by doing the same work out routines he did. Never, I don't have his genetics to get build like that!

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