I've hit an age where I'm more aware of my own mortality. If I follow my my parents' footsteps, I have another 2-3 decades ahead of me, so not THAT close, but I'm more aware of it. I suppose I'm more scared of losing it mentally. Start to see it with people my age, although still not that common. Still, every moment of "that word's on the tip fo my tongue but can't get it," every "oops, forgot about that" feels like a warning bell. Intellectually I'm aware that I don't have those moments any more than I used to, or any more than anyone else, but I feel them more.