How can Some People Recover Repeatedly?

Some people seem to take hit after hit and keep coming back for more. They usually end up like the Grandpa (pictured) in the movie Grumpier Old Men:

Grandpa: Well let me tell you something now, Johnny. Last Thursday, I turned 95 years old. And I never exercised a day in my life. Every morning, I wake up, and I smoke a cigarette. And then I eat five strips of bacon. And for lunch, I eat a bacon sandwich. And for a midday snack?
John: Bacon.
Grandpa: Bacon! A whole damn plate! And I usually drink my dinner. Now according to all of them flat-belly experts, I should've took a dirt nap like thirty years ago. But each year comes and goes, and I'm still here. Ha! And they keep dyin'.

I always thought it would be funny if John (Jack Lemmon) said back to Grandpa (Burgess Meredith): “That’s ‘cause you were the trainer in the Rocky movies!”

In any case, a few days ago I wrote an entry about a family member that ended up in surgery over the weekend. That person is still in the hospital, but now expected to make a full recovery from something that should have killed him years ago. This guy has been near death in a hospital bed so many times, and he always makes it through to laugh another day. Everyone was amazed he had lived so long with this particular problem going undetected – the pain should have been excruciating.

Which leads me to wonder, do the same people who have an extremely high tolerance for pain also the ones who seem to pull through multiple major health events repeatedly? The kind of events that would otherwise kill the average person? Is their pain threshold so high they keep surviving when other people's bodies couldn’t take it anymore?

I realize there is no real easy answer to the question, but the whole past week has got me thinking.

I actually know a few other older people who, by doctor’s opinions, should have been gone already. At this time I can only admire these elders and hope one day I’ll be the one eating the bacon laughing at the experts who said I shouldn’t have lasted through it all.