Background Behavior change and exercise are considered critical for successful self-management in people with multimorbidity, however, little is known about people’s needs, experiences, and preferences. Purpose The aim of this study was to qualitatively explore the perspectives of people living with multimorbidity, healthcare professionals, relatives, and patient advocates in relation to self-management and exercise behavior. Research design Analysis was carried out by means of a hybrid inductive-deductive approach using Framework Analysis that enabled the subsequent use of the COM-B model in relation to the study of exercise behavior specifically. Study sample We conducted 17 interviews (9 focus groups; 8 key informants) with 48 informants from four groups (22 people living with multimorbidity, 17 healthcare professionals, 5 relatives, and 5 patient advocates). Data analysis Through an inductive Framework analysis, we constructed three themes: Patient education, supporting behavior change, and lack of a “burning platform.” Subsequent deductive application of the COM-B profile (applied solely to data related to exercise behavior) unveiled a variety of barriers to exercise and self-management support (pain, fatigue, breathlessness, lack of motivation, financial issues, accessibility, decreased social support). Results Overall, the four groups shared common understandings while also expressing unique challenges. Conclusions Future interventions and/or policies targeting exercise behavior in people living with multimorbidity should address some of the barriers identified in this study.