Is Positive Psychology good for mood & stress?

The evidence points that way, though it's not yet conclusive. A foundational meta-analysis of randomized controlled trials found positive psychology interventions produce small-to-moderate improvements in wellbeing and reductions in depressive symptoms. That's reflected in an evidence score of 62/100 for its role in mood & stress, drawn from 10 studies, with an estimated impact on longevity rated moderate (40/100).