When it comes to coughing, many people see it as a sign of illness. In fact, coughing is a defensive physiological reflex caused by the stimulation of the respiratory mucosa and is a protective response to respiratory diseases. For patients with chronic obstructive pulmonary disease, bronchiectasis, pneumonia, lung abscess and other respiratory diseases, it is extremely important to cough to expel phlegm, expel harmful gases and dirt from the body and keep the respiratory tract open. The lungs are an important organ of the human respiratory system. In recent years, atmospheric pollution has become increasingly serious and there are more and more harmful substances in the air. The toxic substances in the dust, particles and exhaust gases inhaled by the human body accumulate in the lungs and can cause inflammation of the bronchi and alveoli, and even poisoning and carcinogenesis. Therefore, usually when organs such as the pharynx, trachea, bronchi, lungs and thorax are stimulated, impulses are transmitted to the cough center via different afferent nerves, and then via efferent nerves to the vocal cords and respiratory muscles, etc., producing a coughing action. By actively coughing (i.e., coughing even without illness), a huge airflow is generated in the respiratory tract, which can play a role in clearing and protecting the lungs in a timely manner; at the same time, a violent cough can also increase the pressure inside the thorax, which in turn enhances lung capacity and boosts the immunity of the lungs, which is also beneficial to the human body. Therefore, in order to reduce the damage caused by air pollution, bad habits and diseases to the lungs, it is advisable to take the initiative to cough twice to protect our lungs. One of the easiest and most feasible ways is to choose a place with fresh air (preferably outdoors, avoiding dense shade) to do a deep breathing exercise every morning after waking up or before going to bed at night, slowly raise your arms when you inhale, then take the initiative to cough, and at the same time, quickly hang down your arms so that the airflow spurts out of your mouth and nose, coughing up sputum. Do this repeatedly about 10 times. To make coughing more effective, you can drink a glass of warm water first to dilute the phlegm. It is important to note that you should do several normal breaths in each interval to prevent hyperventilation. In addition, for some patients suffering from emphysema alveoli, asthma, chest fractures and other conditions, as well as frail elderly people, this easy way to protect the lungs may not be suitable.