Exercise can impact immune responses to cancer, but the mechanisms behind this are not fully understood. Gomes-Santos et al. demonstrate in murine models of breast cancer that exercise training contributes to tumor control and response to immune checkpoint blockade (ICB). Mechanistically, exercise training induces vessel normalization, increases effector immune cell infiltration and function, and controls tumor growth in a CXCR3 signaling/CD8⁺ T cell–dependent manner. Because of these effects, ICB-refractory breast cancer becomes sensitized to treatment. Exercise also reduces the incidence of lung metastasis. The data support the use of exercise training to improve antitumor responses and immunotherapy efficacy. Read more in this issue on page 765. Original image from Fig. 2G. Artwork by Lewis Long.