I understand the conventional wisdom on the matter mate; I was all over this stuff 40 years ago.
Consider as an example the couple (married, unrelated) who ran 365 marathons in a year. They ate only fruit. Nobody's been able to come remotely close to such a performance. They experienced zero injuries. They had so much energy they ran from the Melbourne CBD to Warrandyte (home, 30-odd kms) upon completion of the year-long task, just for the heck of it.
They were both in their 60s and as I mentioned, genetically-unrelated.