My grandma is 84 and enjoying life still. Granted she can't walk as far as she used to, and gets tired more easily, but she's perfectly cogent and fun to have a conversation with. She's in a retirement village where she has friends with similar interests, and she even plays ping pong weekly. I won't lie, when I last played her a couple of years ago she could still take points off me. I don't think she regrets living past 80, though of course I would never ask.