There are a few diverging representations of the facts in this discussion.
I’m saying physical activity – especially types that increase VO2max, musculature, bone health, balance, agility, and more extend both health and life span. One common tendency I am objecting to is the reification of lifespan as if it were something more than a hypothetical construct (see above). I object not as an intellectual exercise but because it adds little value to posit an invisible function that sets out how long we will live – a lifespan clock if you will. While we may eventually discover such a master regulatory mechanism of this type, if we stick to science, we must acknowledge that we have found nothing resembling it. Moreover, what we have learned through scientific investigation points strongly in the other direction, namely: we all die of something and that something was the terminus bookend of our lifespan. From this it follows that any intervention that forestalls one or more thangs that kill us is therefore life extending. Moreover, beyond the broad notion of physical activity, we see the accumulation of considerable evidence suggesting that structured activities, such as those that that build VO2max, bone health, musculature, balance, circulation, and which optimize metrics such as BP, lipids, BG, HRV and RHR may delay and may in some cases eliminate some of the diseases and life events that kill us.
[None of this is takes a position on maximum aggregate human lifespan which, so far, the evidence suggests no intervention has moved, certainly not physical activity or rapamycin for that matter.]

