There are many other reasons, many elder people are very active physically especially when compared to NA car/suburb lifestyle. This summer I hiked climbed quite a bit in Japanese alps and was struck by number of people in their 60s-70s with massive backpacks, hiking up scary trails at 2-3k elevation. Sometimes I felt scared for them(a couple that we passed on a really scary traverse in rain and lashing wind, both were probably late 60s early 70s?). That are has about 30 lethal accidents a year and since one has to die anyway, might as well fall to your death doing something awesome. This is absolutely different then when I hike climb in Rockies for example, there are always few really hardcore alpinist/climber old school guys in their 60s but almost no retirees doing anything past trailer camping.

On less extreme side, my inlaws play mallet golf religiously. Wake up every day at 6am then they spend most of the day walking around playing, they have a whole room dedicated to their trophies.