People in the West who have been introduced to yoga, primarily Hatha Yoga, come to understand that there can be substantial health benefits to the practice of yoga. Meditation has also been shown to help reduce stress, aid in achieving rest and sleep, and thereby enhance health for the practitioner. With all of these known and supported benefits, we still see that in some people’s minds there is a connection between ill health and yoga.
It is true that extreme austerities can weaken the physical and nervous frame and thus, may indeed undermine basic health in various ways. It is also true that Pranayama practiced incorrectly can cause tremendous disruptions to the energy flow and lead to illness or death. Further, it is true that a practitioner may inadvertently or purposefully open up to various forces from other planes of existence, the energies and direction of which may be harmful to the life-force and the physical being. The practice of yoga may also lead to the action of powerful forces for which the practitioner has not been sufficiently prepared, thus leading to issues in ‘holding’ the force that is working. It has been said that in some cases a master, a guru, may actually take on various karmic burdens of a disciple, and this may have a negative impact on the guru’s health and well-being! In some cases, realized souls choose to take on illness and death to aid others in their spiritual development. The example of Milarepa, who consciously allowed himself to be poisoned in order to convert a jealous opponent.
All human beings are subject to illness and death at this point. Yogic practitioners are not excluded. There are methods to enhance the life-force and physical strength and resistance to illness which some yogic practitioners employ. Thus yoga can actually be a benefit to health.
Any human being who undertakes actions beyond the capacities of the mind, life or body will find that issues arise. Even if the mind is focused, there is still the possibility that vital or physical forces may act to break down the health. Just because someone is practicing yoga does not make him exempt from the basic law of Nature under which we currently live and act. Until that day comes when the body has been fully transformed, Nature will wind up taking its course. This cannot be laid at the door of ‘yoga’ per se. On the contrary, yoga may help to hasten the advent of the longer-term evolutionary changes that will wind up overcoming the body’s receptivity to illness and death.
Sri Aurobindo writes: “There is a sort of traditional belief in many minds that the practice of yoga is inimical to the health of the body and tends to have a bad effect of one kind or another and even finally leads to a premature or an early dropping of the body. Ramakrishna seems to have held the view, if we can judge from his remarks about the connection between Keshav Sen’s progress in spirituality and the illness which undermined him, that one was the result and the desirable result of the other, a liberation and release from life in this world, mukti. That may or may not be; but I find it difficult to believe that illness and deterioration of the body is the natural and general result of the practice of yoga or that that practice is the cause of an inevitable breakdown of health or of the final illnesses which bring about departure from the body. On what ground are we to suppose or how can it be proved that while non-yogis suffer from ill-health and die because of the disorders of Nature, yogis die of their yoga? Unless a direct connection between their death and their practice of yoga can be proved — and this could be proved with certainty only in particular cases and even then not with an absolute certainty — there is no sufficient reason to believe in such a difference. It is more rational to conclude that both yogis and non-yogis fall ill and die from natural causes and by the same dispensation of Nature; one might even advance the view, since they have the Yoga-Shakti at their disposal if they choose to use it, that the yogi falls ill and dies not because of but in spite of his yoga.”
Sri Aurobindo, Integral Yoga: Sri Aurobindo’s Teaching and Method of Practice, Chapter 10, Difficulties in Transforming the Nature, Illness, pp 318-322