Late 30s, I think about death occasionally. It's sinking in that I won't live forever, I'm wasting my life as a wage slave, and there's no do-over. Maybe I should buy a Porsche, that'll fix it.
I have no wife/kids/siblings, so I'm the only one who will miss me. Sometimes I think about the actual process of making sure someone discovers you're dead, so you don't just rot alone for months.
Mum is retiring this year, and starting to get old person health problems, so I'll have to deal with her death at some point, in the meantime she'll just decline from now until the end, which may be in 5 years or 30 years. I remember my gran's last 30 years, she was miserable, and nasty to people, I expect my mum will be the same.