How to study effectively?

So, my hobby and passion is online poker - when I play a session I can hyper focus, mostly for 5-6 hours at a time. I have my off days where I lose focus after 10 mins, but I’ve learnt to “get in the zone” when playing. (Plus the help of nicotine patches) I have lofty ambitions and expectations of myself to become a professional poker player, even if I never reach my goal, if I feel as though I’m making progress towards it, that’s good enough for me. A massive part of winning poker, is consistently studying the game. There’s a lot of things to memorise, reviewing hands, keeping emotions in check, and there’s something new to learn all the time. It’s probably not the best or easiest game for someone with adhd! I recently bought a new poker course, which set me back $1200. I go to sit down to study it, watch one of the 20 min videos, and 2-3 mins in I can’t sit still, start scrolling my phone, look out the window, day dream etc. Does anyone have any effective study strategies that might be able to help in my situation? Thanks!