I've not read the other comments.
I have ADD (not ADHD), may not be applicable. Mum well understood the differences to my older sisters and kept life as calm and stable as possible for me.
She attempted to keep me on a schedule, including eating on time, play time, tidying, studying. The nicest Nun (Catholic School) understood I needed help paying attention, she'd tell me to concentrate. I'm better if people ask me politely.
As an adult, I concentrate better in calm quiet. I eat a lot of protein, I exercise and walk daily, drink lots of coffee (stimulants help calm, strange I know).