Pursed-lip breathing is a technique used during physical activities to control breathing and reduce shortness of breath in individuals with COPD. To practice pursed-lip breathing, sit comfortably, inhale through the nose, then purse the lips as if about to whistle and exhale slowly and gently through pursed lips for four seconds or twice as long as the inhalation. This technique can be beneficial during exercise, climbing stairs, or carrying out other physical activities.