There is evidence that physical activity improves the psychological and physical health of patients with cancer. However, relatively little attention has been paid to understanding their experiences of exercise. This focus group study explored the experiences of women undergoing treatment for breast cancer who had taken part in a supervised group exercise trial. We found that setting up classes solely for women with breast cancer, led by an expert instructor, helped to reduce gender-related barriers to physical activity, such as difficulties in prioritizing exercise over caring roles and worries about changed appearance. For example, some women challenged traditional expectations of femininity by removing their wigs in the classes in order to exercise in comfort. Respondents valued exercising with women in the 'same boat' because of the empathy and acceptance they received and the opportunities to exchange information and form friendships. However, the action-orientated format of the group was preferred to a talk-based format such as a support group; some respondents felt that the 'last thing' they wished to do was to talk about cancer. Our findings therefore challenge stereotypes about women invariably preferring to cope with cancer through emotional disclosure.