1. Knowing that anyone I love can die at any time. On my work browser I'm always getting weird targeted news stories about perfectly healthy people who randomly drop dead or are suddenly diagnosed with an extremely rare and fatal cancer. I'm not afraid to die ofc, but I'm only staying alive for my loved ones and the knowledge that I can't protect them from death or control the world into leaving them alone just kills me. Especially the knowledge that this death will be inevitable someday and there's nothing I can do to stop it.
2. Knowing this is it, there's no going back, no redos or second chances. I spent my teen and college years studying hard and working, so I didn't have any wild stories of dating, going out on the town all night with friends, wacky adventures of self-discovery, etc. I was pretty lonely and shy after a decade-plus of nonstop bullying in school, so all those "fun years" were spent just trying to recover. I'm still in close enough proximity to these years where I'll see a video or whatever of younger people having fun and falling in love and I'll think, "Well if that were to happen to me..." and then I realize that it didn't happen, and it will never happen. I'll never get those years or that youth back, ever. I'm going to be working full-time for the rest of my life just to get by. I deliberately curbed my "fun" in an attempt to secure a good future for myself and just ended up in the same exact rat race, trying to make ends meet, and socially I have nothing to show for it.
3. Knowing how miserable most relationships are. Most of my old girl friends are married to brick-dull slobs who make them do all the housework and childcare (while they both work full time) as they play video games and drink. I'd say only 1 out of 10 people I know are in relationships I envy. Why do I even bother chasing a relationship so much when just about everyone I know secretly resents their spouse? Smh.
4. Knowing that my bullies went on to become attractive and successful in their personal and professional lives. All married and regularly going on cool vacations, going out to fun social events, getting pregnant, making tons of money, etc. Literally no justice in life, what's the point.
5. That we have no idea what happens after death. Personally I believe in an afterlife but it makes me want to CTB when someone thumbs their nose at me and tells me "when we die, that's it, you'll never reunite with your loved ones again lol" as (curiously enough) a pro-life screed. Like okay dude. If I can never hug my grandpa again in the next life, then I'd rather just CTB now rather than suffer with the pain of grief for decades? We won't reunite but at least the pain will end forever?