When a man's health has broken down, nothing seems so important to him as its restoration. It is only then that he really realizes the value of good health. This has been stated from the merely conventional and worldly standpoint. But what of the spiritual standpoint? The aspirant whose health has broken down becomes continually preoccupied with the condition of his body, so that the thoughts and time which he gives to it are taken from the thoughts and time which he could have given to his spiritual aspiration. And when he comes to his meditation periods, he may find it difficult to rise above his bodily states, so that even his concentration and power of meditation may be disturbed by it. For after all, the body is the instrument with which he has to work, and through which he has to achieve his high purpose during incarnation on this earth. This is why systems have been created to lay a foundation of health and strength for the spiritual endeavours of the aspirant. Moreover, if he seeks to be of service to his fellow men, his capacity to serve will be limited by the condition of his health, and may even be inhibited on the physical plane altogether. With good health he becomes more valuable to others but with bad health less so.
-- Notebooks Category 10: Healing of the Self > Chapter 1: The Laws of Nature > # 1