Just a shout out here for medication. ADHD meds are rated effective in the 70-90% range, which is just incredibly good compared to medication effectiveness for just about anything else.

I have ADHD, and hate the feeling of being a victim. "I have this, so I can't do that. It's just the way it is." No! Not for this. Not when there are so many treatment options.

I accept that things may be harder for me than a typical person, that I may have to put in more work than other people to get the same results, that this is something that's very real that I have to deal with and manage at all times. That there will be times when I will fail and my stupid monkey brain will win the moment. But I won't let it define me, I won't let it dictate who I am and what I can and cannot do.

EDIT: Also, I mean to agree with you here: there's a point where no amount of discipline will work, and the advice to "just try harder" sounds like an alien telling you to just grow wings and fly. If you find yourself at that point, medicine can and will help. It also helps you be able to get in a routine of actually doing exercise, which in turn helps even more, and it becomes a sweet positive feedback loop.