I always thought this was my ADHD talking, but from some googling... It could be this as well, or instead of. I'm definitely very monotropic and I also recognize the symptoms of Pathological Demand Avoidance in myself.
Unfortunately, at work I manage three different tracks which each have their own roadmaps and deadlines, so constantly shifting attention is required. It's taken a decade of practice to get where I am -- forcing my body and my brain past perceived obstacles and discomfort. It's possible to train your brain out of certain desire paths with enough effort, but it's not easy, and I wouldn't say I'm cured to any measure. I'm just better at managing my symptoms and getting things done than I used to be.
I hate to say "it's a bootstrap thing" but frankly there's no magic cure, only increasingly difficult iterative steps that you achieve through a ton of practice. I do hope my neurodivergent compatriots here have been able to find jobs that work with their unique skills and brain structures, rather than against as I have found myself.
High school (and all primary schooling) is 50% teaching you useful facts and knowledge and 50% teaching you skills like concentrated work effort, sitting and listening, taking instructions and following them, and applying critical thinking to transform knowledge. MLA falls into the latter category, in my opinion.