as implied, i had an answer in mind myself. interestingly, most of the answers are aspects of what i was thinking. no surprise to me. here it is:
personal responsibility. the minute a person accepts the job of controlling their own health, then one can be as healthy as one desires. the lucky ones do this before its too late. when is it too late? when the dirt hits the top of your coffin.
btw, this is true for the spirit as well as the body.