The physical body is subject of certain limitations. For instance, there is the continuous process of inhaling and exhaling air. It has been found that by slowing down the time taken for inhaling and exhaling, life can be prolonged. The faster the process of respiration, the shorter becomes the life span. There are examples of how this rule speaks. Elephants and men inhale and exhale 12-13 times a minute. By adhering to this time- scale man can expect to live for 100 years. Snakes and tortoises breath at the rate of 7-8 times per minute. Consequently their average life span extends to 200-300 years. Monkeys, dogs and cats breathe at the rate of 30-40 times per minute. Hence their average life lasts beyond 12-13 years. The rabbit breathes at the rate of 40-50 times per minute. Its life span is barely 5-6 years. The faster the rate of respiration the shorter is the life span and vice versa. How is breathing to be regulated? Breathing should be so slow that if soft powder is kept near the nostrils the powder will not be disturbed. The practice of Yoga helps to slow down the rate of breathing in this manner. (D3 , pp. 152-153)