Purpose Physical activity is critical for weight loss maintenance and cardiometabolic disease prevention after metabolic/bariatric surgery (MBS), but few patients meet recommended levels. While difficulties meeting physical activity recommendations are common in the general population, those who have undergone MBS may have unique psychological barriers to activity that impede success, including negative associations with physical activity that are related to a long history with obesity, weight stigma, and physical limitations. This qualitative study aimed to better understand the positive and negative emotional experiences of post-MBS patients with regard to physical activity to inform the development of an emotion-focused intervention to increase physical activity after MBS. Methods Adults who had MBS in the past 2 years completed semi-structured interviews and psychological/behavioral questionnaires. After transcription, a codebook was developed using inductive and deductive methods. Coded data were analyzed using content analysis. Results Participants were 23 adults (78% female). Contexts that contributed to positive emotions during physical activity included an enjoyable type of exercise, social interaction, mindfulness during exercise, and mastery. Contexts that contributed to negative affect were more unique to the MBS population, including all-or-nothing thinking about exercise, using distraction, depression, negative body image, exercising only for weight loss, and the COVID-19 pandemic. Conclusion For most participants, emotional factors were relevant in the decision to be physically active and in their ability to maintain their habits. An intervention that encourages factors that lead to positive affect and addresses factors that lead to negative affect could be effective in increasing physical activity following MBS. Graphical abstract