I've never been diagnosed ADD, ADHD, etc., but when I was a kid 40 years ago, these terms were nonexistant. I guess you were just "hyperactive" or fell into some other category. In my case, whether or not I was any of these I don't know, but I always had a very hard time concentrating at school. Reading especially was hard (but for some reason, I can write just fine.)

Anyway, I've thought many times how riding my bike has helped me. It's hard to describe, but it both stimulates me and relaxes me at the same time. I don't want to live without it, my frame of mind is so boosted and my concentration is, too.