It is def possible. There's a quack on Tiktok claiming ADHD is 'the failure of exec function' and 'no matter what you won't achieve your goals' which is definitely not true. But then he is selling pills, so it makes sense.
ADHD can worsen if:
1. you avoid sunshine and daily walks in nature.
2. don't sleep early and skip morning exercise and breakfast.
3. watch short videos or even long ones for 'fun'.
After taking care of these three, the next step is to claim your attention back by reading long books. It's not that difficult. As all real ADHDs know, even doing toilet needs dopamine and is hard to do (boring). So I place a book on the ledge beside me, and when I toilet, I just read. I've read four such novels in two months now, and all in the toilet!
I discovered now that I can read anything just as fast and my attention stays and my brain works better. Try it. Trollope is great, but only if you're a overthinker like me. I recommend Lewis's "The Monk" if you're into morality/ethics + adventure, or Lermontov's "A hero of our time" if you want to see poetry in prose, and also learn a lot of street wisdom (the kind we ADHDs usually lack). I read both BTW (see my blog for reviews, link on my HN profile).
And finally, don't ever be discouraged. That mental model is easy to fall into, but there are many mental models! :)