Any activity which requires a total concentration of our mind will also control our breath which may even be stopped for a while, e.g. while threading the needle, we stop breathing for a few moments. This shows clearly that there is a correlation between our mind and breathing.
 

It is our common experience that when we become angry or emotionally upset, our breathing is markedly changed in its rate, depth and the whole maneuver.
 

The emotions and the mental activities are related to the nervous system and through it they change our breathing. This means if we try to manipulate our breathing voluntarily, we tackle the life force which is deeply connected with the mind (nervous activity) and therefore with the emotions. 
 

Pranayama aims primarily at the control of the mind. When the mind is standstill, no thought processes or emotional disturbance is possible. 
 

Thus by controlling the mind we would be able to control different emotions and as a result, the temperament, moods, desires and natural instincts of mind (Vrittis) are also controlled automatically.
 

As long as breathing is continued and the air is moving in and out of the body, the mind remains unstable.
  

When breath  stopped, the activity of the mind is also controlled. Thus a yogi attains a complete motionless state of Chitta (consciousness).
  

By practicing Pranayama, the ability to perceive, to know the reality, is intensified. The mind is trained and made capable of the process of Dharana. 
  

Since the mind becomes steady and peaceful after the practice of Pranayama, it becomes suitable and capable to concentrate on one object at a time. 
  

Different nadis are also purified with the practice of Pranayama. This is known as nadi shuddhi. Nadis in yoga are the channels or the passages for the transmission of nerve impulse, or the conduction of the pranic activity, for the circulation of the blood or lymph or even for the flow of air through them. 
 

Most important nadi which opens after the long practice of Pranayama is Sushumna i.e. the spinal cord. 
 

Pranayama eradicates all types of malas from the body and mind. Mala in yoga is that toxic factor which gives rise to an imbalance in the body and mind by obstructing or blocking the normal functions of nadis.
 

Psychologists have shown that the particular type of personality corresponds with a typical breathing pattern.
 

The practice of Pranayama contributes in transforming the total personality. This helps in controlling the non-yogic tendencies, instincts and urges arising in the mind (chitta vritti nirodhah). 
 

In recent years, the scientists have admitted the role of psyche in so called somatic diseases and the term psychosomatic diseases is given to such diseases where the cause is not the infection but the psychic tensions and disturbances. 
 

If Pranayama is not practised judiciously, then many diseases may arise, e.g. asthma, constant hiccup, pain in head, ear and eyes etc. It seems possible since the breathing is associated with the autonomic nervous system (ANS) and ANS is related on the other hand with mental and emotional reactions. 
 

By judicious practice of pranayama, one attains sound health, steady and peaceful mind, slim and lustrous body.