Background: Online cancer support group discussions enable patients to share their illness experience with others. The sharing of technical and emotional support information and the ability to ask for advice are some of the primary discussions shared online. People with bowel cancer can also use these forums to support each other by sharing information based on personal experiences. This type of support provides newly diagnosed patients with advice about several topics, including exercise from those who have been there. Information gathered from online discussion boards may complement the advice received by health professionals. Objective: This study aimed to explore the nature of information related to exercise and physical activity exchanged online for cancer survivors. Methods: A public open access bowel cancer discussion board was searched for threads containing information related to physical activity or exercise. Keywords such as exercise, physical activity, moving, walking, lifting, weights training, and resistance were used to search for threads (online conversations) related to exercise or physical activity. Only threads initiated by bowel cancer patients or survivors were included. From more than 6000 posts, the inclusion criteria yielded 75 threads for analysis. Inductive thematic analysis was conducted across all included threads. Results: Analysis yielded 3 main themes: level of exercise competence, beneficial dimensions of exercise, and faith in the knowledge. Level of exercise competence illustrated the varying definitions of exercise that members of the forum discussed in the forum. Beneficial dimensions of exercise revealed that forum members shared both the spiritual benefits associated with exercise as well as the physical benefits or goodness that they feel exercise or physical activity provides them. Faith in the knowledge of exercise demonstrated that forum members were aware of the general benefits of exercise but felt disappointed that it did not keep the cancer at bay. However, members also had faith that exercise would keep them healthy after diagnosis and treatment. Conclusions: The analysis revealed that people with bowel cancer discuss exercise and physical activity online and that they view exercise as having a mostly positive influence on their cancer journey. However, personal definitions of exercise became a source of conflict within the group. People with bowel cancer seeking information about exercise may benefit from participating in online support groups as it appears that there are many similar others willing to share their personal experiences with exercise. In addition, health care professionals responsible for caring for people with bowel cancer may use these findings to discuss exercise with their patients while being mindful of how they may view exercise.