[fuzzfactor]

It does seem like an unrealistically optimistic point of view for most people, and these are all centenarians who seem to have worked for unbroken decades on end. You would expect a great deal of similarity in their testimonies, but it also might never be possible to be more than halfway similar to people who have only worked half as many decades. Halfway there could get your attention though.

And if you're actually accomplishing something why would you want to quit?