It is pretty easy to tell if you are healthy. You go to the doctor and they test your blood pressure, weight and every couple of years you get a blood panel. There are even tools to make sure you stay healthy. I recently read that if you eat well and not too much, stay active, don’t smoke and only drink in moderation you get 12 to 14 extra years. That suggests that if I continue (pretty much) following all five, I have a chance of lasting past 85.
Link: