Not OP but I think what I went through is really common, so hopefully someone can relate and get checked out.

My grades were fine until high school, when they began to tank. I was constantly comparing myself to my peers, and it got worse with college. I failed out of a 4 year university, and then twice more I failed out of community college. I just couldn't make myself complete a class, so I would stop turning in work, stop attending, or withdraw. Every semester. The only classes I ever actually finished were classes I enjoyed, but I was getting nowhere with GE classes so I quit school. I worked retail and customer service jobs. The discipline of a schedule was good for me.

But I hated myself, and was really down about where I was with my life compared to my friends from high school. I felt incredibly ashamed. I had wonderful ideas and a myriad of hobbies, all of which would eventually because a costly pile of junk, silently judging me for my personal shortcomings. But I didn't know anything was wrong. You develop coping mechanisms, especially if you're an undiagnosed adult. These are difficult to break.

It wasn't until I was 23 and browsing an AskReddit thread much like this one, where someone wrote that they had been destined for a life of inadequacy when they were diagnosed, and a switch flipped. 6 months later I was diagnosed, now a year and a half later I have a 4.0, I'm happy, confident, and a completely different person. For the first time, I have been able to stick to a long term goal.

Medication isn't a magical cure-all, and it certainly doesn't supply motivation or break old habits, but it turns out I can be pretty motivated to do things that I now know I can finish. It's a super neat feeling.