Physical activity increases lifespan primarily by lowering the likelihood of falling and breaking your hip. If you break your hip, your life expectancy is dramatically reduced. If that's your goal, just train your legs!
That said, I think the most important part of exercising is the mental boost it provides. It's like a healthy drug. There are no negative side effects, and it's highly praised by society.
That said, I think the most important part of exercising is the mental boost it provides. It's like a healthy drug. There are no negative side effects, and it's highly praised by society.