I'm 16 and I'm currently being treated for generalized anxiety, depression, and ADD.

I've been somewhat happier and more confident since the start of my treatment (primarily medication), but I often feel fatigued, disinterested in old hobbies, and unmotivated. I can't even finish more than half of a book or TV show without becoming bored. Reading is very, very important to me (and for school), so I'd like to find a way to stay focused. Any advice? Why might this be happening?