I am not trying to be all woo-woo about this, but we live in a time where technology, and not just recent technology, has propelled us far further than we ready for?
I had trouble sitting still and learning in school, but I was able to fake it enough to learn quickly enough to make it through undiagnosed. However, I still caused various other problems i.e. class clown with good enough grades to not get in trouble. Still, I always found school to be tortuous and stressful (I still would if I had to go back).
However, I like to take a step back when things that bothered me like what I mentioned above start to creep back into my mind -- If I were born 100, 200, ... , 9900, 10000 years ago, how much disorder would I have likely faced? I wouldn't have had trouble focusing in classrooms when there were no classrooms for the below average to average person like myself. How would my life have been? Would I have been 'normal?' If so, then maybe... I'm 'normal,' now?
I cannot speak for mental disorders, but I hope my fellows can find peace. We didn't choose this system, and this system doesn't care about us, but when the sun goes down, the moon comes out. I feel like I have a duty to myself to enjoy life, normal or not, because really... It's not like anything life matters anyway.