Energy is the source of everything in the universe. So too, all of the forms in the universe release energy to survive. We humans release physical energy when our bodies take to movement. We release vital energy when we are stirred by our emotions; when there is a will and drive to accomplish something; and when we interact with others. We release mental energy when thoughts enter our mind and when we think. And we release spiritual energy when we connect to our deeper spiritual selves or to the transcendent spiritual reality, or we move to selflessness and self-givingness.
When we are ill, there is an inadequate or unbalanced amount of energy generated in our being. It is indicative that something is amiss. To correct it we need to know the inner source of the imbalance. More often than not, there is a psychological issue at play -- e.g. a wanting habit, attitude, emotion, etc. Attacks of illness can also come to us externally from adverse forces in the environment, including the influence of others through the subtle plane.
Once we discover what that is, and then make the concerted effort to overcome the limitation, the right quantity and balance of energies are restored in our being, enabling the body, the psyche, the emotions, the spirit to become well and whole again. Interestingly the restoration of health can literally happen instantaneous to the discovery of the source of the problem. That is life responding at the physical/bodily level to our change of consciousness within.