Smoking negatively affects physical fitness by impairing lung function, reducing cardiovascular efficiency, and lowering exercise tolerance. The harmful substances in cigarettes decrease oxygen delivery to tissues, hindering performance and recovery. Moreover, smoking can lead to increased fatigue, making physical activity more challenging. Long-term smokers may experience quicker onset of exhaustion during exercise. Quitting smoking significantly improves fitness levels, enhances lung health, and promotes overall well-being, making physical activity more enjoyable and effective.