Hyperactivity

I was hyperactive as a boy, but now it's anxiety. 

Butterflies in my stomach have fangs. 

One of my closest friends is ADHD. He always says if he doesn't schedule an at least 5days of the workout, he can't focus. 

Is this something available to you? Or interesting even...

Like every day.  Even now.

Most of my time at Uni was that.  Sit in a lecture theatre, have no clue what was going on, fall asleep, get grief from friends and lecturers for falling asleep, rinse, repeat.  Of course I had no diagnosis back then and had always been bored with long lectures, so just went with it.  I would prefer if i'm given something to read, do some research online, and then I will understand it.  Even better if the lecturer gives you the topic for the week after.  Some did as soon as they realised that I didn't work quite the same way as everyone else.

In hindsight, going to Uni was one of the more pointless things I did in my life.  I would have been better starting down the route I am on today.

So yes, struggling to concentrate just happens, a lot.