Somewhere along my years of growing up and living, I got the idea that all our medicinal needs are found in the food we eat. Mother Nature has made sure that we are taken care of. So, I eat all food in moderation. I swim and walk - exercise, which I believe is the other component for good health. I don't take supplements and medicine. And unless I am really sick, I stay away from the doctors. So far, I have been lucky in that, I am still fit and healthy.
The other thing is, I don't think I want to live forever. I would rather go when my faculties start failing me. Just like when you go to a party. You had fun and then it comes a time to leave. You might want to stay on a bit longer, but it wouldn't be fun anymore. Best to leave when you have enjoyed yourself so that the evening will be a nice memory.
Even if my faculties are intact, it would be sad to see everybody around you dying while you live on and on. It must be very depressing and lonely. :-)