Inspiration doesn't come easy. Most of the time you just have to put your head down, start writing and get into the story. Once you bury yourself in the detail, the inspiration flows. It's important to work within a framework instead of just writing blind. This gives you a set of goals or milestones to work towards within the story. Sometimes an exciting piece of the story becomes an inspirational drawcard so you write until you reach it and then the passion really flows.