I spent my 30s feeling like a retiree, but then I bought a bicycle at age 39 and started riding 25-50 miles a day. Now I'm approaching my 60s and I'm in the best shape of my life. Barring catastrophic and permanent injuries, I think the main problem with aging is that being sedentary causes your body to decay and the older you are the more time you've had to be sedentary. Get up off your dead asses, people, and don't tell me you don't have the time for exercise. You have plenty of time to watch TV and scroll through your phones, turn some of that time into something useful.