Oh... yeah, I've been there since I was like 12, ha. More seriously as I got older -- I haven't expected to live to retirement age for well over a decade, now. I sorta' take care of my health (mostly because I'm caretaking for my grandparents, but once they go *shrugs*), but, like... not nearly well enough, and between likely inherited issues that's probably not far from kicking up and being poor in a poor area in a shit, shit state, I just don't expect to last that long. Nothing about my life or health or family history or environment suggests it's likely.
It's not entirely a bad thing, though? At last part of it comes from just being okay with dying. I've been up mountains, in caves, from one side of the US to the other. Swam in the ocean, in lakes, rivers. Helped build and repair a house or two, all sorts of stuff. For all I've spent a lot of time as what amounts to a techno hermit due to a lot of reasons (mostly just... hating where I live, pretty intensely, heh), for a long while now I've felt like I've done enough, y'know? I've lived a life full enough to be content with kicking the bucket, and there's precious few people likely to outlive me that I give much of a damn about, so no regret-y things on that front. Long as I can manage shelter and food and something to read I'm pretty content with the thought of just mostly just reading a bunch for another decade or two and then getting to have the best nap ever, the one I don't have to wake up from.