Previous research indicates that performing positive activities boosts happiness. The present studies examined whether neuroticism would moderate the sustainability of the effects of positive activities on happiness. Study 1 showed that the effects of counting blessings/kindness daily for seven days lasted a week after participants stopped performing the activity, but only for low-neuroticism individuals (who reported increased happiness) and not high-neuroticism individuals. However, a week post-intervention, gratitude-/kindness-listing participants were more likely to choose an amusing rather than a sad film, regardless of neuroticism differences. This suggests that behavioral choice is more sensitive to positive intervention effects than self-reported happiness. In Study 2, high-neuroticism individuals who occasionally visualized and wrote about their best possible selves over three weeks were happier than their counterparts in the control condition. The present research illustrates that although neuroticism moderates the sustainability of positive intervention effects, encouraging continuance of positive activities may produce more lasting effects.