Exercise can help to increase our lung capacity, which means you can take in more oxygen with less effort and better efficiency. Greater lung capacity can improve your endurance, especially if you like to run, jog, swim or engage in strenuous exercise for 90 minutes or longer, 3 to 4 times each week. Long distance runners and marathon runners are among those who need maximum lung capacity. One of the benefits of aerobic exercise, like swimming and running, is an increase in lung capacity and improved cardiovascular function generally. Breathing exercises focus on improving lung capacity and efficiency. If you suffer from any kind of lung condition like asthma or cardiopulmonary obstructive disease (COPD), check with your doctor before trying lung exercises. 

Breathing by using the abdomen, or the diaphragm, can help you improve lung function. The muscle primarily responsible for breathing is the diaphragm. The diaphragm is located between your chest and your belly. When the diaphragm contracts, air is drawn into the lungs and the belly expands outward. The function of the diaphragm is unconscious, and we breathe without even thinking about breathing. You can take control of your breathing by taking slow, deep breaths using the diaphragm. In addition to improving your lung capacity and oxygen stores in the cells, breathing exercises can help you to relax and improve your overall sense of well-being. 

Become aware of your breathing by placing one hand on your belly and the other hand on your chest. Relax your abdominal muscles and breathe in deeply through your nose. The hand on your belly should move out farther than the hand on your chest. Pull down with your diaphragm to fill your lungs completely. It may take some practice, but after a few deep breaths, you should feel the air being pulled into your lungs as the diaphragm moves downward and the belly outward. Hold a deep inhale for about 5 to 7 seconds. Exhale by pushing all of the air out of your lungs through your mouth. Continue to exhale by pulling your diaphragm upward for about 5 to 7 seconds. Repeat this breathing exercise for a total of 5 deep inhalations and 5 deep exhalations. Sit on a chair to perform this breathing exercise the first few times you do it, in case you experience some mild dizziness. 

If you sit in a chair to do deep breathing exercises, sit up straight and look straight ahead. Drop your shoulders down and back to straighten your spine. Relax your hands, palms down on your thighs. Perform this exercise twice each day. When standing to do deep breathing exercises, stand up straight by dropping your shoulders down about one inch and push them slightly toward the middle of your back. Place your hands on  your hips with your elbows pointing out to each side. Relax and then begin your breathing exercise.