Absence of mental ease and equanimity leads to what we correctly call disease. One sacred duty of the doctor is to advise persons on how to preserve health and prevent disease. He has to be vigilant in society to discover and suppress every tendency in Aahaar and Vihaar (food habits and recreational activities) by which diseases are developed. The dress worn by humans, the houses where they live and the areas where they are situated, have to be tidy and clean. The food that is taken has to supply all the elements needed to keep the body strong enough to resist illness. Even if it falls short a little in this respect, health can be maintained if it is unpolluted, pure and holy. The atmosphere breathed in, the water taken in, the ground lived on, the animals and plants that surround---all have maleficent microbes that may cause illness if the mind and body are not equipped with powerful resistance armour. 

…Sathya Sai Baba, “The doctor's profession” Divine Discourse, September 1980                                           http://www.sssbpt.info/ssspeaks/volume14/sss14-53.pdf

You should all realise that the human body has been given to you solely to render selfless service. Such service broadens the heart, destroys the ego, and generates bliss. Service also helps to promote consciousness of the brotherhood of man and the Fatherhood of God. Your task does not end there. You have at the same time to propagate the idea of Ekaathma-Bhaavam (spiritual oneness of all mankind). Mankind has to be led from dualism to non-dualism.

... Sathya Sai Baba, “Spiritual significance of loving service” Divine Discourse, 21 November 1995                http://www.sssbpt.info/ssspeaks/volume28/sss28-34.pdf