The relationship between fitness level and immune function is multifaceted. Regular physical activity enhances the immune system by improving circulation, facilitating the efficient transport of immune cells throughout the body. Moderate, consistent exercise has been shown to lower the incidence of infections and boost the body's defenses against illnesses. However, excessive training without adequate recovery may lead to a temporary dip in immune function, increasing susceptibility to illness. Striking a balance through a well-rounded fitness program can bolster immunity while promoting overall health and resilience.