It is not necessary to take exaggerated breaths and it is essential to perform the exercise whilst remaining physically and mentally relaxed. Many people engage in meditation to overcome stress and illness and finish up worse than before because they push and strain in meditation. There are a number of variations on this meditation linked to colour. One is to think of the colour white whilst inhaling the OM, to think of red whilst holding the Ah at the heart and to think of blue whilst exhaling the Hum. Those who practice this exercise, diligently, every day for a few weeks will soon start to notice the benefits.
Mantras are very powerful healing aids.
They are not simply sounds in the conventional sense but are the resonance of subtle primordial energies which we have within ourselves, the vibrations of which distribute gentle healing energies throughout our being. Most healers have their fair share of failures. Often it is said that when a patient doesn't get better it is because he does not wish to get better. Such a case is difficult to heal and sometimes not possible at all. The Buddhist solution is to purify the negative karma and Buddhism teaches many methods of purification.