Sometimes, you come to a moment in life, and think I'll never forget this moment. You wonder where you will be in five, ten or twenty years, but something tells you when you look back from then, you'll remember this place in time.
Like sitting beside the fire at my neighbors house and hearing my husband say, "Yeah, I'm definitely doing the military this time." Until that moment the prospect was 93% yay, 5% maybe, 2% nay.
This is the moment in a movie--the music playing, the action, the change has happened and in 5 minutes you watch the main character go from mild-mannered accountant to ripped, edged, cunning soldier over the course of several months[okay, that's me fantasizing... ;D]. This is the moment in the book you are reading, when the Hero accepts the Call to Adventure and Crosses the First Threshold. This is the start of the story... This is when things get dicey, when trials must be met.
What makes your book stand out? What does your hero have on the line? Will he risk everything to get what he wants? It's the emotion behind this risk that pulls your reader into the story so that they can't put the book down.
...and whatever you do, have a happy ending!