The body wasn't meant to be immortal. Its systems, including the nervous system, decline. As the brain is deprived of nutrients, higher thought processes peel away, one by one, usually starting with short-term memory. If the course continues long enough, the mind reverts to ever more primitive states, which is the reverse of how it progressed from infancy into adulthood. Dementia sets in, the children put you into a containment facility with attendants trained to treat you as a child, and you lose interest in living. Before that happens to me, someone please hand me a loaded shotgun.