Dispositional self-compassion has been linked to better mood and better health behaviors in numerous studies, albeit in cross-sectional designs employing self-report measurement. This study (n = 42) experimentally evaluated how a self-compassion (versus self-criticism) manipulation impacted patterns of positive and negative emotion, tested whether it increased health behavior (flossing) and motivation to floss following negative feedback, and assessed whether changes in emotion predicted changes in behavior. As expected, there was greater positive and less negative mood following the self-compassion induction, but only temporarily; there were no buffering effects of the self-compassion intervention on mood after critical external feedback. In contrast to expectation, self-compassion predicted lower floss time and did not impact motivation to floss in future. These findings suggest that while being kind to oneself instead of self-critical may promote better mood, it may be less effective in motivating certain health behaviors like teeth flossing, at least in an experimental setting.