The pants'ers are going to argue with me on this (I spent a long time arguing with myself), but in order to make it through writing the dreaded middle of a book, I really feel you have to understand your beginning and end.
Let's pick this apart a little...what IS the middle? It's a whole lot of information and actions that you're not going to really care about--might not even make sense--without the beginning of the story. And if you take away the ending, none of the actions or information given are going to go anywhere either.
This is why most writers hate the middle. Because everything that takes place in the center of the story has to make that brilliant concept or idea hold up. THIS is where you sit down with your amazing hook about futuristic germ people falling in love despite their dystopian disinfectant environment and have to ask yourself...but what actually happens?
I'm feeling a little lazy, so let's think of the beginning and end of Twilight (JUST the first book) out of context:
Beginning: Human girl meets sexy/angsty/tortured boy.
End: Girl gets the freaking CRAP beaten out of her by a total psycho with a grudge.
Without knowing the middle--OH, he's a sparkly vampire who wants to love, but has trouble restraining eating human girl--it's difficult to really care about the tortured boy or whether the girl will die in the end (if you have a stone cold heart like me).
Vice versa, would you care about a girl who is in love with a vampire stalker for no apparent reason? (don't answer that question). The middle is just as disappointing on its own without the rest of the donut...and so Edward Cullen is basically cream filling (go wherever you want with that).
My point, if I haven't lost you completely by now: Even though the MIDDLE is the place where most of us tear our hair out, consume vast amounts of sugary foods, and ask ourselves why we ever thought this stupid idea could work in the first place... It's because the middle is where your concept transforms from IDEA into STORY. And if there's nothing of substance in there, all you'll have in the end is a disappointing donut.
Emily Hainsworth is the author of THROUGH TO YOU, (Fall 2012 Balzer+Bray / HarperCollins), a sci-fi novel about a seventeen-year-old boy grieving for his dead girlfriend until he discovers she's still alive in a parallel reality--one where he's the one who died. For more information, visit her website.