I probably ought to try this, but I don't think I would have the same motivation. Nothing like having to get home prepares you to do 20 more miles! I am somewhat concerned about the safety of riding in traffic, so at least half of my riding is on MUPs. Almost got slammed by a deer last Friday, so I really don't know.

OTOH, I do spend a half-hour on my rowing machine every day, which is kind of the same thing, though just to get my real boats on the water would take at least an hour and a half so the motivation is convenience.

The real point is that activity is essential if you want to maintain your health well into your senior years. Perhaps the medical community will wake up and abandon their standard that assumes that some health switch flips when you hit 65. I'm tired of hearing that age is a significant risk factor and that I positively need this or that because of the age-related guidelines. If something is not recommended for a sedentary 40 year old, why should it become essential for a healthy 65 year old?