RecruitingBehavioural interventionPositive Emotions Following Acute Cardiac EventsThe focus of this study is to test the efficacy of a 12-week, remotely delivered, positive-psychology-motivational interviewing (PP-MI) intervention, with additional twice weekly text messages for a total of 24 weeks (with interactive, algorithm-driven, goal-focused text messages in the final 12 weeks), compared to post-acute coronary syndrome (ACS) treatment as usual, in a randomized trial of 280 post-ACS patients with low baseline physical activity.