Just about everyone with an unobstructed nose will breathe through their nose when at rest or during casual activities, but most people will breathe through their mouth during exercise. The more intensely you exercise, the more likely that you will have to breathe through your mouth because you may not be able to get enough air through your nose to feel comfortable. Possible Advantages of Breathing Through Your Nose Why would you even consider trying to control whether you breathe through your mouth or your nose? Compared to mouth breathing, nasal breathing: helps to filter out pollutants helps to filter germs adds moisture to the air you breathe heats the air you breathe may reduce asthma attacks in people who suffer from exercise-induced asthma. Nasal Breathing Takes Practice You can breathe far more air into your lungs through your mouth than you can breathe through your nose. You can exercise …