We assume happiness is stable, an endpoint to achieve or a goal to chase. But it isn't. Social psychologist Jennifer AakerÑwith her colleagues Cassie Mogilner and Sep KamvarÑhas discovered that happiness changes meaning in systematic ways over the course of our lives, shifting every five to ten years. Through experiments, surveys, and blog-based data (http://wefeelfine.org/), their research also shows that these changes are malleable. Although many argue that happiness is a choice we make, this work suggests that we can change our meaning of happinessÑand the meaning we choose can impact the choices we make. This year at FoST, Aaker will explore how our definition of happiness changesÑand how understanding this can help us rewrite our own life stories.