My best friend maybe age 6 up to early 20s was severely ADHD. Back then it wasn't called that, but we all knew she was different. She got diagnosed as an adult and no one was surprised. So for me, that was what ADHD was. She never knew where her keys were, kind of out of control a lot. I always had a pretty good grip on things and was pretty calm a lot.

I never thought of myself as ADD, even if I could only focus on "fun" things, constantly daydreaming, always starting new projects I lost interest in soon and so on. I was diagnosed when I was 40 (doc thought I had it when I was 38 but there was a waiting list), and I sort of accepted pretty fast I had a lot of ADD traits, even if I've "seen worse".

Reason why I thought I couldn't have it was that me and my friend weren't similar at all. She was wild and crazy while I was the one listening patently to all her problems. I guess it took me a while to understand the ADHD is a spectrum too, not just one thing.