An online ‘positivity’ exercise involving the practice of discrete positive emotions was pitted against a mindfulness meditation exercise and an active placebo control. The effects of positivity and meditation were examined in relationship to personality variables known to entail vulnerability to depression. Participants (N = 741) were randomly assigned to the positivity, mindfulness, or control condition. They completed their exercise for three weeks and were assessed on measures of subjective well-being at baseline, post-test, and one, and two months later. Results indicated that all groups showed significant decreases in depressive symptoms from baseline to two months. The positivity exercise uniquely predicted increases in meaning, pleasure, engagement, and satisfaction in life across follow-ups. Dependent individuals responded favorably to the positivity intervention in the short run, but worsened in the long run for pleasure-related happiness. Self-criticism was associated with significantly greater gains in life satisfaction following exercise completion.