Nobody trains like him, and few ever did. There are only a few guys including Hank Armstrong who remind showed in the ring the type of endurance than Mayweather posseses. I think his style, Mayweather, that is has a style that is more tiring than most other boxers, all his movements are very quick and explosive which are the most tiring and he throws every punch with all his power. When guys, other champions, or competitors, so I've heard pros including Corley say that they've never ever seen anybody train even close to how Mayweather does. He goes up to 15 rounds of 5 minutes with different sparring partners comming in after skipping for half an hour high intensity, doing intense bag work... I've never seen a guy look so fresh 12 rounds into a fight, he is probably the only guy who is the exact same when he enters a fight as when he leaves in terms of his speed and ability to think in the ring and that shows his great work ethic.

The guys who come to mind who are the closest to his work ethic are obviously Hopkins, Wright a few years ago, Roy JOnes jr a few years ago(Though he tired late in fights, but his style was even more tiring than Mayweather's because he also threw combinations.), MIguel Cotto, Manny Pacquiao... I am really surpised nobody has said Manny... he is the closest by far, and I am only considering post 2000.

Other guys are Evander Holyfield, Meldrick Taylor trained like a mofo, Leonard was in great shape as a pro, Hagler, Saddler, Frazier and Ali(when he felt like he needed to).