ADHD is a blessing and a curse. Anything you don't enjoy doing becomes very difficult, and it takes a lot of conscious effort to turn doing those things into habits so they'll stick.

However, people often ignore that there is an equal and opposite side to that coin, and people with ADHD can hyperfocus to an absurd degree on tasks they enjoy. An internet connection and a desire to learn something is a powerful combination for someone who can shut out everything else in the world for several hours at a time.

If you have a job you enjoy, ADHD is usually a boon. Unfortunately, high school is mostly stuff that falls into the "very difficult" category.