The reader has to believe that this character has her own reason for taking this action. Success is a pro-active motivation because it draws the character forward towards itself. 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.