In Ashtang Yoga, mental growth through Pratyahara and Sadhana has been emphasized upon. The body is therefore under the control and direction of the mind. Human mind has been divided into three categories depending upon its qualities or gunas.

Sattvic Mind: A Sattvic mind is completely at peace and cool like the moon on the full moon night. Its chief characteristics are kindness, truth, contentment, love, devotion, humility and happiness. In this state, the blood pressure remains normal and the living cells multiply and become stronger. They obey the orders of the mind without any hindrance. The person endowed with this type of mind can control and develop his body at will.

Rajasic Mind: In this state, the Sattvic traits of the mind are overshadowed by the cleverness of the intellect. The mind then gropes in the darkness of worry, sorrow, jealousy, greed, anger, fear and luxury. In such a state, blood circulation becomes abnormally rapid and leads to turmoil and confusion in the body. The cells are also in a disorganized and disturbed state. Their growth and development is stopped and their deterioration and weakness begins. Any amount of exercise and diet cannot then save the body from disintegration. Body health is therefore bound to suffer.

Tamasic Mind: When we start feeding ourselves on the poison of two deceit, theft, ignorance, laziness, violence, adultery and other sinful activities, then our attitude towards life also gets distorted. We start taking pleasure in all these debased activities. Our thinking is completely blurred, because our blood circulation is so disorganized that the cells stop their normal functions. They start getting filled with poison instead of life. None can save such a person from his doom.

It is now obvious how mind can influence the body. Mental health is the first condition not only for the growth and development of the mind, but also for the body. It is therefore all the more necessary to acquire Sattvic mental traits through constant effort. In fact, physical and mental health is inseparable. One cannot be improved at the expense of the other. If the mind is sick, it will not allow the living cells to grow and become strong. And if the body is sick it will make the mind helpless, because it cannot control and direct body functions.