Now that we are retired we thought walking and bicycling would be good exercise. Well basically it is. The only problem we have found is being nearly run over either by cars not stopping at crossing or being injured when a bicyclist flashes by on the sidewalk. In California the pedestrian supposedly has the right of way, if you are on a crosswalk a car supposed to stop to let you pass, but in Los Angeles most of the time they do but it is that one time when they do not that I worry about. So walking has its dangers.
I always got annoyed by people cycling on the side walk. When I finally got a bicycle of my own things changed. While on the street, the traffic nearly knocked me off my bicycle several times. That's why I started riding on the sidewalk for safety. Funny how thing change.
So that is why we think walking and bicycling in retirement can be dangerous to your health. Lets face it as we get older any injury takes longer to heal.