After they retired were? Which fighters never let themselves go, kept training and still stayed in shape long after they called it a day? It's always baffled me that Boxers who keep themselves in tremendous condition for say 10-20 years suddenly let it all go. Now I know a lot of depriving goes on (got to stay around your weight class weight, not stay out and party etc), but some Boxers go off the boil... BIG TIME (no pun). Which ones never though?
Duran used to party and get on the pop between fights strangely didn't seem to affect him much went on for years.
I think Floyd's probably the winner here. However, if you're looking for an example of an active fitness regimen in somebody who enjoyed excellent longevity, Jack Sharkey jogged three miles daily in support of his avid outdoorsman lifestyle, competing against Ted Williams in fly casting events, a baseball legend he enjoyed a friendly fishing rivalry with. Sometimes you really can't go by physique all that much, but the kind of outstanding shape Sharkey kept himself in is evident during his exemplary officiating of Moore-Durelle I. I've actually watched this classic three times just to break down Jack Sharkey's performance as the referee, and it's a third man clinic. He's not remembered for his career as a referee for exactly the reasons one should not be. A great referee should not be noticed, and Sharkey wasn't. Included in that ability is the physical condition necessary to stay out of the way, yet cut in quickly to call a halt if punching continues after the bell, as he did. Ken Cooper's somebody else noted for a daily three mile jog. There's some evidence that this distance may be optimal for long term maintenance, and Jack Sharkey did it for a long time before Cooper made the term aerobics famous. Max Schmeling was a beekeeper. I don't know that he had a dedicated fitness regimen like Sharkey's jog, but he successfully returned to competition a year after his beating in the Louis rematch, then again after WW II following grievous combat wounds as a paratrooper in Crete. Given the opportunity, he might have rivaled Moore's athletic longevity with his pugilistic template. For a fitness regimen to support good health and biological longevity, moderation is critical. Schmeling and Sharkey had it, and became the first two former HW champions to become nonagenarians. (Incidentally, I've personally known three winning triathletes who died of cancer in their early 30's, and Cooper's clinic in Dallas is researching how too much exercise undermines health and shortens life expectancy. What good are washboard abs if they're on display in a coffin? Die young, leave a good looking corpse?) Wouldn't be surprised if Vito Antuofermo maintained excellent physical condition. Even when not training for a bout, he ran five miles daily, something perfectly sustainable through a long retirement as a habit. Joe Frazier is an example of somebody who I wouldn't hold a loss of shape too much against. Arthritis is a real shoot of the dice as to whether or not one gets nailed with it. Ditto diabetes. Smoke did not inherit great genetics (his father died at 53), but learned decent eating habits to deal with the diabetes, and 67 is a reasonable life span when factoring in all he had stacked against him. He wasn't Busters Mathis or Douglas, and probably lived a good deal longer for having been a champion boxer than he would have lived if he'd never been an athlete. I wouldn't hold the development of arthritis against any retired boxer blocked from remaining physically active because of it. Hagler's been an action movie star in Italian cinema, so remained in shape as a matter of course.
With cases like Marciano's, there's no mystery to me, because there was no moderation with Rocky. It was all or nothing. SRL, on the other hand, maintained a very strong routine, and always began his training camps below the weight limit of the division he was competing in. While Bruce Finch was running 15 miles a day in training, Ray only needed to run a few. Keep in mind that some folks are just naturally slim regardless. Michael Spinks seems to fall into this category, as did Bob Foster. (BF might have been mentioned favorably in a thread like this before his health began failing, but 76 is still a reasonable life span. Ali's parents both died at 77, and he'll be 74 in January.) Guys like Norton and Weaver were just blessed with naturally muscular physiques. I don't know what to make of Holyfield or others from the steroid era.
George Chuvalo was in decent shape, considering the tragedy in his life he could have just drank himself to death. I don't care if BHop isn't legitimately retired...he's in pretty good shape for a 50 yr old.
Jim Corbett stayed in great shape through his whole life. Even sparring with Tunney in his fifties. Jack Dempsey also stayed in good shape. Always went on a morning run well into old age. Sugar Ray Leonard, Tyson, and Evander are in very good shape as well.