I have a 15 year old son that was diagnosed with ADHD at 5 years old. We tried everything, diet, timers, therapy, and drugs. From all of these years of experience, all I can say for sure, is it is up to the child. Offer incentives, not bribes, take away favorite toys/activites when he doesn't do as he should. In other words, expect him to succeed, and never ever let him use his condition as an excuse or a crutch. What seems to have worked better with my child than anything was simply being honest with him about his condition, but at the same time making sure he understood that yes, it may be harder for him to concentrate than it is for other children, but other children have other sometimes more serious conditions, and they still succeed if the will to do so is there. Of course all children are different, and ADHD may be more severe for one child than another.