Exhale and then inhale. While exhaling make a quiet ‘sss’ sound with your tongue. The ‘sss’ sound must be even and last as long as possible, so hold back the exhalation. Feel how the bulge at the solar plexus gradually comes out more and more while you sustain the ‘sss’ sound. The bulge must not diminish, and must be kept expanded. Remember to keep the ribs expanded all the way around and gradually pull in the abdomen around the navel, straighten the curve of the back, and keep the muscles of the back contracted. Sustain the feeling of holding back your breath while the air is gradually released. You should continue practising until the ‘sss’ sound lasts for one minute.