Studying needs a period of condensing notes then learning, covering for self test, learning, covering etc...
So you are fit, don't watch TV, are interested in your subject but cant get down to it. Are you sure that you are not doing things that are more interesting than studying? Just a question.
I cannot tell you what to do, I apologise if my list above sounded like "telling". Good luck and best wishes.
But we haven't even met!