Where does Yoga begin and where does it end? Is not the whole of your life Yoga? The possibilities of illness are always there in your body and around you; you carry within you or there swarm about you the microbes and germs of every disease. How is it that all of a sudden you succumb to an illness which you did not have for years? You will say it is due to a ‘depression of the vital force’. But from where does the depression come? It comes from some disharmony in the being, from a lack of receptivity to the divine forces. When you cut yourself off from the energy and light that sustain you, then there is this depression, there is created what medical science calls a ‘favourable ground’ and something takes advantage of it. It is doubt, gloominess, lack of confidence, a selfish turning back upon yourself that cuts you off from the light and divine energy and gives the attack this advantage. It is this that is the cause of your falling ill and not microbes.
Ref: Questions and Answers 1929