Interesting. I've often contemplated about it. I don't think I want to live past 80. I mean unless there would be a medical revolution where you can retain youth or slow down aging significantly.
People's experience change their perspective. What's important to you now will change. What you're able to appreciate changes.
If you remain active through your life, I think you're much more likely to stay active as you're older. I intend to retire by 40, but I don't intend to be idle.