It could be so many things, so hard to give advice. For me, a big part of it was sleep related, and I could only fix it with medication; if you have adhd it may be similar. The medical issues gave me the feeling of I’m painfully bored but my body refuses to do/enjoy anything, and I just want the sweet release of death deep sleep.

On the other hand, I was also so used to delaying gratification for school/work that I literally didn’t know how to enjoy myself. I think finding the little things that bring you joy and incorporating it into your daily/ weekly/ monthly routine helps a lot. Something like: on Sundays I get to eat pizza or if I reach my short-term goal/milestone, I’ll take myself to the cool place I never get to go to. I started doing this after getting a dog. So literally train yourself to love life like a dog.