Smoking negatively impacts physical fitness by reducing lung capacity, impairing cardiovascular health, and decreasing overall stamina. It restricts blood flow and oxygen delivery to muscles, which can hinder performance in both endurance and strength activities. Moreover, long-term smoking is associated with a higher risk of chronic diseases, including heart disease, which can further decrease overall fitness levels. Quitting smoking can lead to significant improvements in fitness and overall health, enabling individuals to participate in physical activities more effectively.