Why is running good for health?

I started running at 66 and am still running nine yrs later. I' ve run dozens of 5k races and have gotten first place in all but two. Got a second and third in those. It pays to be an older runner...not as much competition!

not good for the knees

wish I could run, never been able to.

walking is also best

I preferences using stairs. I do 4 rounds of 8 flights everyone day.