You probably stay healthy because your workout makes you happy! That kind of "walking" workout is similar to running or jogging- a good stress reducer.

I cannot say I do that well (but I think I have a few years on you and definitely a few inches shorter legs!) My "workout is a 6- mile loop with 300 feet gain (hey, we do not have many hills in Sacramento)that I do in 1 hr 45 minutes. I love my loop down by the river- I get to see wildlife, fishermen, scoot through oaks and it even has a half-way restroom. I do not go the gym much anymore. I really do not like the entire gym scene (indoors, smelly, loud).

Does your dog get to go with you?