Perfect Age to Die?

Growing up I never thought I'd make it to 18, but here I am 19 and still alive. I've struggled with suicidal ideation and stuff which explains my way of thinking back then. And I'm not fully "cured" or whatever now, but even aside from that I just can't imagine myself growing old. I was watching an anime earlier and someone in the comments started off with "I'm 40..." and I genuinely thought to myself "damn". I just can't imagine being 40 and doing the things I enjoy now like indulging in K-pop, anime, manga, etc. What would I even need to live that long for? It really stumps me idk how people can just keep going idk Maybe it's cause I don't really feel like I have a life's purpose yet. I'm just a random college student. Maybe once I get a job or something I'll think differently. And maybe it's just my poor mental health thinking this, but idk I feel like even without it I'd still think the same. I just feel like on the inside I'll never grow up as fast as I'm aging.