5x is arbitrary and just how I chose to express the relative importance of doing nothing --> walking --> running. That's just my mental model. I.e. walking has

5x is arbitrary and just how I chose to express the relative importance of doing nothing --> walking --> running. That's just my mental model. I.e. walking has no excuse barring disability. Running I recommend, but not as strongly. Put another way, I will endlessly nag my parents on walking. Running or jogging I merely suggest, given various costs like you point out.