I feel like mindfulness is the key. It's such a meme word, but being aware of your thoughts and redirecting them to something else is sometimes the only way to get out of mental doomer spirals. It might not work so great sometimes, but it gets easier and easier to get out of these destructive ruminating loops the more you try. It's a skill, just like riding a bike.
Speaking of skills, pick one up. Exercising is one of the easiest ways to get free dopamine, not because "exercise good and healthy" but because when you practice a technique, or add more weight to the bar, you're giving your brain the satisfaction of "task completed successfully". The physical health benefits will come with that, of course.
Try to think of something "grounding" eg something that brings you back to reality. For me, that's work which is kind of sad but it's something concrete and real that I can focus on. I don't really get happy or excited about shit, so if I'm going to do something "pleasant" (exercise, going out for dinner) I "remind" myself that even if I don't get that anticipatory pleasure, I will enjoy it in the moment. You have things that you enjoy doing, too, but depression or autism or ADD or whatever steals that joy away from you. But that doesn't negate the fact that you can have meaningful experiences.
Reminding myself that I'm not a jeet who lives in a 3rd world country also helps, but not everyone is that privileged. I'm lucky to be among one of the most privileged groups in the most materially comfortable countries on Earth, and I don't want the opportunities afforded to me by the accident of my birth to go to waste. Hopefully, you share the same circumstances!
Oh, and take some fucking vitamin D. 5000-10000 IU of D3 + K2 (you need the vitamin K to absorb the vitamin D!) a couple times a week has helped my mental state immensely. So many people have vitamin D deficiency and they don't even know it.
Just by making a few mindset changes I'm happier than I've been since I was a lil' Postal Dude, and this is without therapists or psych meds. Best of luck to you fren, I hope you can crawl out of that Dark Mirror Hole because it ain't fun. I'm still fighting my demons, and you probably will be too for a long time, but know deep down that this gay life is worth struggling through.
