Evidence suggests that regular physical activity (PA) and exercise can improve health and wellbeing following a cancer diagnosis and may help reduce cancer recurrence and mortality and prolong disease-free survival in cancer survivors. However, few cancer survivors are regularly active and many fail to meet the recommended PA guidelines. This is a major area of concern as for survivors to achieve the long-term health benefits associated with PA and exercise, they must be habitually active. The overall aim of this thesis was to explore PA and exercise participation in adult cancer survivors, with a specific focus on group-based PA and exercise. Study 1 explored cancer survivors’ perceptions of general PA and identified specific barriers and facilitators they experience specifically related to group-based activity. Qualitative methodology was employed and underpinned by the PRECEDE component of the PRECEDE-PROCEDE model. A unique finding from Study 1 was the group-based format of the exercise program being a key facilitator for PA and exercise participation. Study 2 evaluated the feasibility of a virtual home-based exercise intervention utilising the RE-AIM evaluation framework and explored participant experiences transitioning from a gym-based to home-based setting to exercise during the COVID-19 pandemic. A mixed-methods approach was employed to evaluate each dimension of the RE-AIM framework and additional qualitative methods were employed to explore participant experiences. High levels of acceptability and satisfaction (feasibility) were reported by participants, significant improvements in physical fitness and mental health were observed, and the group-based format and coach were reported as key facilitators for adherence to the intervention. Study 3 identified and critically reviewed the literature exploring the effect of home-based PA and exercise interventions on PA, physical fitness (PF), and quality of life (QoL) in cancer survivors. The effect of home-based PA and exercise interventions on PA, PF and QoL appeared complex. There was some evidence for the positive effects of home-based PA and exercise interventions on PA, PF and QoL in this population, particularly those with aerobic exercise components and additional support. Assessment tools used, and outcomes reported were variable, specifically for PA. Overall, there is a need for standardisation across studies in terms of assessment methods that will facilitate future reviews in this area.