That's true to an extent, but maybe there's more to it than that. The older people I know seem to have more, well, I'm not sure how to put it... Willpower? My psychologist is an elderly woman and she says that if she decides she ought to do something, she just does it. What she feels doesn't matter. My older relatives act like that too. Their ability to endure emotional (and physical) pain and keep going is remarkable.