I've been diagnosed last year, at 34, and my life has started making so much more sense.
Wish I got diagnosed earlier — getting a mathematics PhD with untreated ADHD was double plus ungood.
I didn't know anything about ADHD, and was sure I don't have it because it's described as "deficit of attention" (spoiler: it's not).
I realized I need to look into it after relating to one too many ADHD memes.
In the aftermath, I have written an ADHD Meme Wiki[1], which helped me (and several other people!) get diagnosed and understand ADHD better: