Rene Descartes’ hypothesis of mind-body dualism has long been discarded, as the mind and body are parts of a continuum. At the holistic level disease is a byproduct of stress, which is an agency (physical, chemical, psychological, microbial, or environmental) which tends to alter the internal environment of the organism. The attempt of the body to maintain homeostasis, i.e., a constancy of internal environment involves complex processes collectively designated by Hans Selye as the General Adaptation Syndrome (GAS) with three fairly well defined stages of alarm, adaptation, and exhaustion. The limbic system is responsible for the maintenance of homeostasis, and has great resilience and ‘coping’ capability. 

Chronic stress repeatedly induces this syndrome, which at the biological level works through body chemicals like adrenaline and corticosteroids coming from the adrenal glands sitting on top of the kidneys. During life we oscillate between alarm and adaptation, and ‘cope’ with the stress. The moment adaptation is shattered we step into the stage of exhaustion, and ‘diseases of adaptation’ set in. Today we are working full throttle at breakneck speed using our reserves faster, which by nature are meant to last a lifespan.
 
Thus diseases of adaptation (stomach ulcers, migraine, diabetes mellitus, hypertension,
coronary heart disease, cerebral strokes, arthritis, premature ageing, and mental disorders like depression and schizophrenia) strike at a younger age.

It is said that to avoid the ill effects of stress one must not take life too seriously. In medical parlance a change in life-style is advised, which is easier said than done. 

Mood (emotion) is an expression of a complex chemical transmission across various components of the limbic system, placed deeply and securely in the brain. The limbic lobe is the oldest part of the cerebral cortex and includes the amygdale, anterior thalamic nuclei, cingulate gyrus, fornix, hypothalamus, prefrontal lobes, and connecting pathways of the brain. Among these the key player is the hypothalamus which mediates nonverbal behaviours through the reticular formation, which when excited causes arousal in the cerebral and spinal circuits, and vice versa. Moods also have a large genetic component. As a unit the limbic system regulates many aspects of behaviour like pleasure, anger, rage, fear, biological rhythms, feeding, learning, survival, sexual pleasure, genital swelling, grooming, courtship and maternal behaviour.        
          
Medical science today recognizes that emotions such as anger, fear, sorrow, envy, resentment and hatred are responsible for about 60 per cent of human sicknesses.
 
It is said, “Two men look out of the same prison bars: one sees the mud, and the other the stars”. It all depends on the mental makeup. Among various neurotransmitters regulating human behaviour, lately serotonin and oxytocin have been found to play an important role. Oxytocin has been found to maintain healthy interpersonal relationships. Release of oxytocin from the posterior pituitary creates affectionate feelings. It is also released during sexual orgasm in both sexes. Seroronin has been labeled as the civilising neurotransmitter, and oxytocin as the hormone of love.

Since we have little control over the stress factors (stressors) that bombard us, one must learn to: (i) diversify stressful agents; (ii) avoid long exposure to stressors; and (iii) develop a proper attitude of mind by practicing yoga and meditation. To lead a ‘healthy and happy’ life a good plan would be to divide time between work, play and worship. Humbly, think more of others than you do of yourself.   
 
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