[balding_n_tired]

I was a decent recreational runner in my late 20s. But pain tolerance is not "the difference", just "a difference". I do not have the classic marathoner's frame, and at above 60 miles per week, I would start to feel twinges here and there, which likely would've developed into injuries had a continued to train at that level for more than a couple of weeks. Now, 60 miles per week is nothing for a marathoner, about half what the true stars run.

As with any form of highly competitive athletics, the best advice is to choose your parents carefully.