Life isn't worth having if your health is failing and pain and suffering becomes a daily reality.
Me, I'm 47, and I feel about the same as when I was 25, but my recovery time from intense training is greater, no question. But still growing stronger.
I assume when I'm above, say, 75-80, I'll be happy to jump off this ride. Wouldn't be surprised if I keel over much sooner, though. Just ... because. No big thing. Men in my family tend toward aneurysms. Hardly ever heart disease/attacks.