I'm unsure your first point can be true. The pinnacle for a 37 year old is surely lower than for his 23 or 24 year old incarnation, if both life stages were given the same fitness programme. 37 is still very young, but there's already some trace of physical deterioration by then, most apparent in athletes who in almost all sports aside from golf, are off their peak by then.
> Most people your age can still exceed any physical accomplishment they've had in their lifetime if they really want to. E.g. they can play sports better than they ever had and they can achieve personal bests in any physical ability.
So not people who were at the peak of their ability/potential in their 20s – most people, however, do not perform at their limits in their 20s, simply because that isn't their priority, they don't train for it, etc.
They're saying that you can be the best shape of your life beyond your prime potential years because almost nobody reaches their potential in their prime, which is trivially true, not that you can perform better at 37 than a theoretical maximum in your 20s that you never achieved.
