As the Rebbe teaches, the body mirrors the soul – this is not only in the actual measurements, as a psychiatrists told me, studies show that the feelings we have produce chemicals that can be measured (which is obvious, think, adrenaline, dopamine etc.) but the technique to a healthy or sick soul is exactly the same as healthy or sick body – and fundamentally it all boils down to diet – so the most important question you must continually ask yourself is: "what am I feeding my mind, hence heart, hence self" (as well as my body)