Things that make me a bit crazier than you'd expect

Sometimes when I'm reading, I imagine that the characters are people I know. It started when I was reading something really boring and some character reminded me of someone, so I started to imagine it because it'd be much less boring. It makes some readings really exciting.
The thing is, sometimes, I really like a book and that's down to the way I imagined the story and characters. This can also happen due to different contexts and phases of your life: sometimes you can't appreciate a book because you're too stressed or you're bored, whatever. It's strongly dependent on our moods.
Obviously there are times when the books are simply too bad and there's no way you can make them seem better. :)
Other times, you don't have to imagine any characters because the writer makes you "see" them so clearly.