The turning point came when I was living in eastern Ukraine serving a Mormon mission. As per the mission rules, the only books we read were scriptural, we only used a computer for 30 minutes a week to email home, and in my particular mission I spent 90% of my time, every minute from 11 AM to 9 PM (except for a one-hour dinner) walking around, talking to people in the streets.
I don't know if it was age or that I was finally rid of the many stimulants I used to have, but my mind just slowed down. I concentrated on everything, and, perhaps especially because I was speaking Russian, I could literally recall every word of every conversation I had. I sat down in the mornings and studied the intricacies of the Russian language for an hour straight without blinking an eye. I read the Old Testament cover to cover; something that would have made me literally pull my hair out just a year earlier.
Then I went home. I got an iPhone, I got on the Internet, and it all came back. I try to limit the stimulants, (I've become very minimalistic), and I usually spend a lot of the morning with a calmer mind, but... I work online. I love the Internet. And I haven't yet been able to calm my mind like it was for those two years.
It may be a matter of self-control - it probably is, but learning to program is incredibly painful. 10 minutes at a time sometimes with an incredible number of stops and starts.
I don't know what the answer is, nor do I pretend that I can project my experience onto some greater understanding of what ADHD is, how to defeat it, or if it needs defeating, but the experience of feeling like I could finally do all the things I wanted to do because I didn't have anything else to stimulate me was fascinating, and it may be valuable to someone else.