Motivating movement AWAY from something. Guilt is a reactive motivation because it propels the person away from itself. This affects the trajectory of the plot. Most motivations have both a negative and a positive aspect. Internal motivations are what will individualize your character.
Story is the actual action of the book.
Give the character something immediate to inspire action today. And motivation, especially that created in the past, doesn't have to remain static. Consider the protagonist's journey through the book. This will involve a shift from the original motivation. Make sure there's sufficient provocation for this shift, and thus for her development.