The book I recently finished writing had a gestation period of over five years. It started with and idea that I wrote three scenes about. Then it sat for years. I'd pull it up, look at it, not know how to proceed, then put it away again. I had no clue how to make it a story.
When I finally decided to embrace the crazy, and take creative writing classes I found the key. It started with a video of Amy Tan (JOY LUCK CLUB) talking at a conference about voice and perspective. It struck me that I was writing a third person perspective about things that I had in small ways experienced. So I changed what I wrote to the first person and in four weeks I had 50,000 words and a real story.
I wrote in beast mode. I woke up and in the shower knew exactly what to write that day. After work, I wore my fingers out punching the keys. I sat there without ever needing to get up. Eating and drinking water was a burden. I could write deep into the night without feeling tired. Then I could go to sleep thinking about what needed to be written the next day. Then I did it over and over.
Don't get me wrong, it had a lot of work to do. It was absolute crap with an unrealistic romance, unlikeable characters, and a completely illogical ending.
But writing beast mode was addicting. And it started because I figured out the perspective that story needed.