Let me tell you something I tell many people:
I had ADHD. It was a medical condition. This is why I am disgusted by all teachers and their "zero-tolerance." If I see a teacher acting like this and I didn't know better, I'd think, "So this is how all teachers treat their students." Have a thought about that.
If you treat someone as an outcast and five years later, you change into a completely different person, that guy will always see you as the jerk you once were.