Dr Christopher Booth discusses the CHALLENGE trial, the first randomised controlled study to demonstrate that structured exercise can improve cancer survival. The trial enrolled 889 patients with stage III or high-risk stage II colon cancer across six countries, comparing standard lifestyle advice with a supervised, long-term exercise behaviour change programme. The intervention led to significant improvements in disease-free and overall survival, with a reduction in cancer recurrence and in the risk of death. Dr Booth highlights the affordability, sustainability, and policy implications of this approach, arguing that structured exercise programmes should now be considered a new standard of care and integrated into routine cancer services worldwide.