Recently I started reading Rodman Philbrick's The Last Book in the Universe. I got about halfway through it in one sitting, and since I'm a slow reader that's pretty good for me. But then I had to go do something else. I put the book down and I never opened it again.
I don't think my attention span is shorter than a ten- to twelve-year-old's, which is the age group the book was written for. What got me halfway through the book was suspense alone. It was pretty tense. There was lots of menace and danger. I wanted to see if the characters were going to die. But there was nothing to keep me reading except suspense and once the tension was broken by me putting the book down, I didn't care enough about the characters to come back to it.