When the mind is engaged in carrying out some idea, or the vital being is involved and enthusiastic about something, there is a strong tendency for the rise of Rajas in the being. Rajas has a tendency to overdo things, go beyond limits and as a result, it is the frequent cause of injury and the effects of over-straining or over-indulgence that fall on the physical body. This can lead to the rise of Tamas, when the enthusiasm wears off and the body is left exhausted and worn out. We do not often consider the current limits of the physical body, nor the way to systematically develop strength, endurance and capacity in the body and in our impatience we create issues that can set us back.
Those who are engaged in physical culture recognise the importance of bringing the body to a peak of performance through systematic training, development and proper care given to its needs for food, fluids, rest, and recuperation time, interspersed with the training and development regimen. They find that the capacity of the body far exceeds what most people recognise as their limits, but this only occurs with a balanced program that does not injure or break down the body, and which respects its needs for systematic, patient development of its capacities.
For the seeker in the integral yoga, another process enters into the equation. The body can be made a conscious and willing participant in the process rather than simply being imposed upon by the mind or the vital force. With the descent of the higher force, the body can experience a new sense of wide calm, peaceful flowing energy and a feeling of intense bliss that makes it such a willing participant.
Sri Aurobindo writes: “The first rule is — there must be sufficient sleep and rest, not in excess but not too little. The body must be trained to work, but not strained beyond its utmost capacity. The outer means without the inner is not effective. Up to a certain point by a progressive training the body may be made more capable of work. But the important thing is to bring down the force for work and the Rasa of work in the body. The body will then do what is asked of it without grudging or feeling fatigue. Even so, even when the force and Rasa are there, one must keep one’s sense of measure. Work is a means of self-dedication to the Divine, but it must be done with the necessary inner consciousness in which the outer vital and physical also share. A lazy body is certainly not a proper instrument for yoga — it must stop being lazy. But a fatigued and unwilling body also cannot receive properly or be a good instrument. The proper thing is to avoid either extreme.”
Sri Aurobindo, Integral Yoga: Sri Aurobindo’s Teaching and Method of Practice, Chapter 10, Difficulties in Transforming the Nature, Weakness, Fatigue, Inertia, pp 309-311