If you have a cold, flu, sinus congestion it does not always flow into the other nostril easily. Like everything it takes practice. You can purchase a neti pot at most yoga centers or at the Himalayan Institute. A typical yoga posture affects the heart and pulse rate, breathe, blood circulation, endocrine glands, organs and digestion. Every posture has an equal and opposite postures to remove any tension from the spine.
Every posture involves breathing.
Specific postures massage and tone the internal organs. Postures improve oxygen intake, strengthen the lungs and improve digestion. Over a prolonged period of practice it affects right down to the cellular level. One is able to regulate one's breathe and to control the autonomic nervous system. The conscious breathing help to oxygenate the body on a cellular level to organ to bloodstream.