One of my teachers once described the artistic process for acting as "filling up a basket." She explained that she had to gather the pieces of a character--history, thoughts, emotions, everyday activities-- to "fill up her basket" before she set foot on the stage. If the basket wasn't full, the character would be flat and wooden.
This makes sense: real people are always "full baskets." We don't walk around as tabula rasas waiting for something to stimulate us. Instead, we carry a host of internal qualities and motivations that constitute who we are.
I think of the writing process as a similar filling of a basket. I let my mind fill for a long time with different elements of a novel (or, in the past, an academic paper). When all the elements are in place, the basket overflows and I am ready to begin. A great deal of the process of story-building is subconscious or intuitive. Story-building requires technique, but the technique is so complex that once mastered, it operates invisibly in the back of the mind. I can tell myself "something is missing in my conception of this character," but I can't force the right solution to appear by my conscious intellectual analysis. There are too many variables. instead, I discover the perfect solution for a plot or a character through a kind of intuition that I've picked up from reading a huge number of really good stories over the course of my life.
As the basket of my second novel has been filling, I have been aware that something crucial was missing from it. Yesterday, I figured it out. My first novel had a theme drawn from personal beliefs so deep that my passion for the novel was consuming (and still is, when I think about it). I had to develop a theme for the second novel that was equally-consuming for me, but different. In order to do that, I finally realized that I need to change my protagonist in a fundamental way to express the second novel's theme. He is very different from how I initially imagined him, and that difference will be the making of the second novel. One of the keenest pleasures of writing occurs when the obstacles melt away and the story is about to begin!