Because I'm lazy.
Well, lazy people don't get good grades. That's just how school works, it has nothing to do with intelligence.
I'm lazy but yet I am on high honors in school. A's and such all over.No teachers have problems with me.
Then you aren't lazy.
Let's just say you don't want to do it.
Draw the curtains, lock the door, turn on the light, shut down the computer(s), move all books and unrelated things away and listen to music. You should listen to music, complete silence used to be a form of torture.