So back drop: I'm a 23 y/o male who just started working in a foreign city.

So last night I couldn't sleep and I kept thinking about my childhood and kept reminiscing on random memories of being a kid, watching my favorite cartoons, playing Nintendo 64, and just appreciating on the sheer joy I had as a child since I did not know how the world truly worked and I lived in my own bubble. I became lost in the moment of pure nostalgia, almost as if I was there living right there in the past as a 12 year old boy. I started crying and I couldn't think of anything but feeling sad and empty. I mean my life is great; I'm working, I lift everyday, I'm confident, but I don't know whether to feel shameful or to take and learn from this experience. Anyone is free to laugh at me or w/e, but I really want to know how have you guys came to terms with being an adult and coming to terms with the fact that your past is just a memory and nothing more. It hurts whenever I get lost in these nostalgic thoughts as it makes me realize that the world once felt pure and that there was no weight on my shoulders for responsibility.