Yoga has become so popular because people are realizing the benefits of yoga.  When yoga is taught correctly, the breath is used to help people ease into postures, strengthen their bodies, ease tension in their minds, and fill them with a sense of inner peace and calm.  The yoga breath is done with a full inhalation through the nose, and a full exhalation out of the nose with the mouth closed.  Because we walk around shallow breathing most of the time, the “complete” yoga breath is powerful for reducing stress in our bodies and minds.  Try this simple exercise.  Get in a comfortable seated position (you can do this in a chair).  Close your eyes and inhale a breath through your nose fully into your lungs, then exhale a breath completely out of your lungs with your mouth closed.  When you exhale make sure that you exhale so completely that you have to take another breath.  Practice the breath daily.  Work up to 30 breaths or to as many as you feel comfortable doing.  After completing your breaths, slowly open your eyes and notice the difference in how you feel.