Larry Holmes. His amazing recuperative powers and longevity of his career was greatly helped by his amazing stamina.
I know, I'm a nuthugger but Patterson was always ready to go, regardless of some of the outcomes, whether it be 10-12-15 rounds. Unlike many other fighters he once said he 'broke' training camp at least three days prior to the fight saying: (paraphrase) "You don't want to leave everything in the gym, you've trained for weeks so you're not going to be out of shape with a three days rest; plus, I've always found that, as those three days go by, your mind and body gets 'antsy', wanting to fight, which prepared me better. I would come in hungry and ready to go". Interesting take on preparation IMO.
The title literally says shape, not health, shape. Bodybuilding is not a healthy activity, but it is the act of shaping the body. Fat is also unhealthy so even if we were just discussing who comes healthy fat ****ers would still be a laughable claim.
Tito Trinidad always was in great condition. He didn't have that bodybuilder physique but he ran marathons in his spare time. You could tell by the way he never stopped pressuring and he carried his power late.