ADHD is a brain-chemistry difference that results mostly in the person having a dysregulation of motivation. When you tell kids that they have ADHD, you should also be telling them that they do not have a case of bad, stupid, or lazy.
The Three Best Provisions for ADHD
Structure
Structure is obvious for many parents. Same bedtime, predictable consequences, predictable timing of activities during the day, etc.
Motivation
ADHD people are not able to get themselves motivated for tasks that do not interest them. They do not have an internal dialogue to be a cheerleader for themselves, especially for boring tasks (like homework).
Parents/Teachers are advised to provide the motivation to complete these tasks. Learning is faster with direct reward rather than allowing avoidance or loss of privilege.
Novelty
Motivation means novelty and reward. Many tasks can be made into novel games. Rewards need to be changed and incentives tweaked regularly to keep them novel. Without novelty, interest cannot be sustained.