. . . the researchers looked at 65 different mortality risk factors as they tracked participants through the later years of their lives. Once the number crunching was finished, the factor that rose to the top was surprisingly simple and straightforward.
The most sensitive measure of longevity was the individual’s own subjective evaluation of how healthy he or she felt. In other words, a person reporting that he or she feels healthy outweighed any other single predictor of a long life, including any medical measures such as cholesterol levels and blood pressure.'
It's hard for someone with diabetic neuropathy or COPD to report "I feel healthy." Unless they lie. Unless they just haven't been to the doctor in years and don't know better. Having a positive attitude and a fulfilling life is different. I have a friend about 80 with a wonderful sense of humor, bright fulfilling volunteer life, and so many ailments she should be in a text book.