> I get bored or distracted easily, I don't believe in ADHD, but according to the definition I definitely have it.

ADHD isn’t some genetic on/off switch that determines whether you can focus or not, it’s a threshold for commonly-linked traits that indicates you may benefit enough from medication, routines, and special accommodations in certain circumstances that it’s worth it to try them and for you to be evaluated differently from people who don’t pass that threshold.

Not believing in ADHD is like not believing in charisma or any other observable set of traits.