I have read many of us have a biological clock that goes off in the late 80s, if not before, and regardless of exercise, careful diet, not smoking etc lots of people decline fairly rapidly after that. Even were that true, the quality of life until that point will be a lot better with daily doses of bike medicine. In my opinion, there are only 4 critical things required to enjoy retirement....enough money to not worry about it all the time, people you love, your health and something you are interested in. Bicycling hits the last two for me. Dogs are good too.