It is said that service starts with the tongue.  Sevonmukhe hi jihvādau.  Tongue, which is the most difficult sense to control, has two primary engagements that it likes – vibrating with various sounds and tasting good food.  Now the trick is to optimize and perfect this engagement.  The tongue should vibrate only transcendental sounds.  And the 100% perfect transcendental mantra is the Hare Krishna mahamantra.    Another function of the tongue is to taste nice food…so best to serve it spiritualized, and disinfected food, in the forms of remnants of food offered to the Lord  – His prasadam.  When the tongue is thus engaged, all other senses will be controlled automatically.   So in essence, chanting is the medicine, and prasadam is the diet.  Bhagavad-gita 17.1-3 — Honolulu, July 4, 1974

The standard of civilization on the basis of unlimited sense satisfaction has to be changed into regulated life for spiritual realisation and that will lead to the actual moral standard of life. In the diseased condition of life nobody can be happy increasing the standard of sense gratification. If he wants to get rid of the diseased condition he has to consult the experienced physician for guidance of diet and medicine. And to relieve the diseased condition of the present set up of Godless civilization the leaders have to consult the liberated physicians who have already prescribed the right medicine and right diet. The right medicine is very simple. They must attend to hear the transcendental messages from the Lord and the diet is prescribed in the matter of partaking the remnant foodstuff which is first offered to the Lord. Back to Godhead Magazine, Volume 3, Part 14, November 20, 1958

There are many hospitals and medical clinics to cure bodily diseases, but there are no such hospitals to cure the material disease of the spirit soul. Just like a man diseased, he can be changed into a healthy person provided he follows the medical rules and regulation, takes medicine, diet and… That is possible. So if one does not follow the regulation, rules and regulation, he remains there, diseased.

The principle is to purify ourself.  Just like when a man becomes sick, he has to purify himself by regulative principle, by diet, by medicine, similarly, we have got this material disease, covered by the material body, and the symptom of miseries are birth, death, old age and disease. So one who is serious about getting out of this material bondage and free from birth, death, old age and disease, so he must take to this Kṛṣṇa consciousness. Arrival Lecture — Mexico, February 11, 1975,

Every disease takes some time for its being completely cured but the treatment must begin without delay.