I have seen the opposite effect in my grandmother. She is definitely not on a mission. She just wants to live as long as she could, despite outliving pretty much everyone her age group and also her children. She's never been saying "when I'm gone..." or stuff like that, like it was not a possibility. But she often liked to say to other people something along "don't do this or you will die" - i.e. "don't work too hard because you will die". People much younger than her. Never said something like that in context of herself. The only exception is recently, after my father's death she asked my mother: "will you take care of my funeral?" but then she shortly added "if you live long enough that is" or something like that. My mom is 58 and grandma is 93.
I think it's a bit like ego thing and positive feedback loop. She takes pride in her longevity.
I think it's a bit like ego thing and positive feedback loop. She takes pride in her longevity.