Chronic diseases are complex conditions requiring a range of health professionals to support lifestyle behavior change, with research indicating that interprofessional teams yield the most positive outcomes. Yet, little is known about the factors influencing collaboration between health professionals. This study aims to explore factors influencing interprofessional collaboration in health professionals involved in lifestyle behavior change (psychologists, exercise physiologists, and dietitians). Semi-structured interviews were undertaken with a convenience sample of 14 health professionals (four psychologists, seven exercise physiologists, three dietitians), individually or in small groups. Results from thematic analysis highlighted factors influencing collaboration in clinical practice at three levels: Systemic, professional, and client. Subthemes revealed time, financial costs, client consent, attitudes, role understanding, contact with other professions, interpersonal factors, accessibility of services, and profession-specific perspectives influenced collaboration in practice. In addition, psychologists were viewed as useful in specific areas of practice, with some unique barriers identified. The results suggest a need for barriers to interprofessional collaboration to be addressed, such as by co-location, exposure to other health professionals, and direct communication pathways. Implications include possible systemic changes and education to aid interprofessional practice in chronic disease. Further exploration of collaboration in broader professions and sectors, and client factors is recommended.