One of the unfortunate (or fortunate) aspects of life is that we all grow old. For all the advancements in science, there is no way to stop this process. We can mask it for a while through manmade cures, exercise, positive thinking, and even surgery, but in the end, we all grow old. This is one unalterable fact of life.
There is a biological component to this, to be sure. Our bodies grow weaker in time, our organs work less effectively, our hearts pump less blood, our lung have a smaller capacity to push air, and our bone density diminishes. No one can stop this. Moreover it is not just a simple dichotomy of the body or the mind. Everything and everyone grows old and eventually dies. This is a fact of life.
There is no clear cut and provable answer to this difficult and vexing question. See the link below for a discussion of the factors that may affect the aging process and what is currently suspected and understood about the process of aging.