The NYT has an interesting article up about the controversial question: what dose of exercise is best?
"Two new, impressively large-scale studies provide some clarity, suggesting that the ideal dose of exercise for a long life is a bit more than many of us currently believe we should get, but less than many of us might expect."
Basically, you can get a log of positive effect just by working up to something vigorous walking for about an hour each day. After that, any increased benefits plateau. You hit a point of diminishing returns.
Curiously, they didn't find a point at which a steady high dose became life-threatening. There has been some worry about that - about possible cardiac problems arising specifically in heavy-training marathoners, for example. But, at least on net, they didn't see that in their longitudinal studies.
As I always tell people, you can get a lot of the benefit of exercise without much suffering. It's not all about masochistic marathon training or grueling CrossFit routines. Those things seem to be good for you, but the big long-term benefits are low-hanging fruit, that require effort, but not all that much effort.
So, anyway, an hour a day of moderate exercise is highly beneficial.
If only some lab could make it,
into a little pill,
requiring no act of will,
then everyone would take it.