You scored again (I like the specificity, as opposed to the vagueness of many Medium health articles). The simple answer might be "in retirement, as much exercise as you feel comfortable doing, without injuring yourself". For me at 66, that is 30 min vigorous treadmill daily, 3x45min weights/bike, 2x30min swim weekly (total 450). Thinking of adding 5x10 min burpees but don't want to overdo. Like diet, you have to like it or you'll stop (actually for diet I load up on berries, nuts, pico, mushrooms, chicken, eggs which I never get sick of). I can feel it working, the sleep deeper, and I never have anything more than minor aches (and the usual battle w constipation). I never would've had time pre retirement for this, but then I probably didn't need it as much then (I was a builder/farmer, they never consider non-gym minutes in these things, but believe me I was burning a lot of calories in my previous daily regimen!). Great comment about early sports, if 30% doing h.s. sports, they need to get that up to about 75%. Getting excited about going outdoors (wo hurting yourself) is the key to longevity and (more importantly) loving life? I believe if you are doing that 300+ weekly exercise min. in retirement (w 30g fiber/day) you can also lapse a bit on your diet?