Understand always that the physical is a representation of the spiritual. One could say that all illness is derived from separation from source, the incomplete expression of the source of all love and truth, but how does this separation occur? Of course it occurs with the ego where there is a sense of a separate identity, a separateness that you identify with. And so the energy and the tension and the tiredness come about because of a lack of alignment. You might say that the ego expends a lot of energy holding on to certain kinds of self-concepts.