Evidence shows that regular exercise lowers the risk of developing breast cancer and breast cancer recurrence. The causality of this relation was examined in this study (1). The typical recommendation is 150 minutes per week. The hypothesis is that exercise lowers the basal systemic levels of cancer risk factors. Another process is possibly the acute increase in several potential anti-cancer components during each exercise bout. The authors reviewed the evidence. Overall and in conclusion, the authors propose that transient increases in exercise factors during acute exercise appear to be mediating the positive effect of regular exercise on breast cancer remission.