Lying flat on your back with your head lower than your body, place your left hand on your upper chest and your right hand on your abdomen. Inhale deeply through your nose, while pushing outward with your stomach so that the right hand can feel the abdomen rise. Try not to move the left hand while inhaling. In other words, breathe in with your stomach muscles, not your chest. Purse your lips and exhale slowly, pushing the abdomen inward and upward towards the ribs with your right hand as you do so. Try to exhale as long as you can before inhaling again the same ways as before. Once you have mastered this breathing technique, the breathing may be done at other times throughout the day.
Try to do about 100 of these deep breaths a day. 10 sets of 10 work well.