Individual experiences of ADHD remain varied - it sounds like you have some significant executive dysfunction (I do as well), and it responded well to your medication. I'm really happy for you!
I get so tired of popular wisdom that assumes that all people experience life in essentially the same way, and that the 'recipe for success' should be universal. "Discipline" is a nonsense word to the folks with executive dysfunction, you might as well tell us that the key to personal success is learning how to fly. Everyone else is doing it, so it must be easy - you just need to try harder!