I can't believe that the 'elderly ' topic is still going, especially from @Oaktree55
As someone else said, at 35 you've considered geriatric if you're pregnant.
Considering that almost 70% of the population are overweight /obese, at ages younger than him, he's probably fitter than many younger people.
Age is only a guide to fitness and health.
People are more predisposed to certain conditions as they age but the vast majority (not all) are entirely lifestyle-related and preventable .
For someone like MM who's made his living out of keeping fit and helping others to do it, he's not your typical overweight, unfit 67 year old.
IMO he's had a very unlucky and unfortunate accident where h e has probably fallen into the sea, either through heatstroke or whatever was ailing him when he set off.