We can always choose to stop vibrating with unhealthy emotions. We can always choose to vibrate unconditional love rather that the forms of fear of loss of love. The slowest level of the body continuum is the physical body. It's the slowest body to react to changes in the overall being and the last to manifest healing. The physical body is the barometer of the total state of the person on all levels and his overall health.
Unconditional love is the absence of restrictions in the flow of energy that creates the body.
In the absence of restrictions the state of health is robust. Health problems can be seen in the energy bodies as restrictions and stagnations even before they manifest in the physical body. The restrictions of stagnation of essential energy may be seen as separation from God or the fear of separation from God. If all things are manifestations of God Stuff, universal energy, real separation is impossible. It follows that disease, as well as all other life challenges result from the illusion of separation from God.