Efficacy of Positive Psychology Interventions to Increase Well-Being: Examining the Role of Dispositional Mindfulness

There is increasing evidence that positive interventions enhance well-being, although benefits for individuals will partly depend on the congruence between their unique characteristics and the requirements of an intervention. In this study, dispositional mindfulness was examined as a potential moderator of the efficacy of two interventions: three good things and best possible selves. These interventions were expected to increase positive affect and mental well-being and decrease negative affect, and it was hypothesised that participants high on mindfulness would benefit most. In an online randomised controlled trial, 211 participants (159 women, 52 men, M _age = 34.00 years) completed baseline measures of well-being and mindfulness, and were randomly assigned into a 7-day intervention or a no-activity control group. Results from 73 participants who completed Time 2 indicated that best possible selves significantly lowered negative affect, with a medium effect size. Follow-up data from 37 participants 2 weeks later indicated that for participants with lower initial mindfulness, those allocated to the best possible selves group experienced increased positive affect, with a large effect size. Motivation to do the assigned intervention was strongly and positively associated with practice, and both motivation and frequency were strongly related to increased mental well-being. These results provide additional support for the efficacy of the best possible selves intervention and indicate that it can be beneficial for individuals with low levels of dispositional mindfulness.