Regular exercise can significantly improve immune function by enhancing circulation and promoting the flow of immune cells throughout the body. Physical activity can increase the production of antibodies and T-cells, which play crucial roles in fighting infections. Exercise also supports better sleep and reduces stress hormones, both of which are beneficial for the immune system. However, it's important to balance exercise intensity, as excessive training can have the opposite effect. Overall, engaging in regular, moderate exercise can bolster immune defenses and promote overall well-being.