From a psychonutritional point of view we FIRST need to treat the biological disorder that is responsible for "mental" symptoms, and then, there after, treat the psychological aspects (retraining the mind as it were). People who tend to have a "mentalistic" point of view of human behaviour, often tend to confuse symptoms for causes. Aberrations of the mind are then seen to be caused by the mind, instead of the body.
Breathing exercises, meditations, yoga are examples of Management Techniques, that may give temporary relief but do generally not "cure" the disease.