The process of Krsna consciousness is to chant Hare Krsna and to hear the sound attentively so that the mind is fixed upon the transcendental vibration of Krsna's name, which is nondifferent from Krsna the personality. The real purpose of controlling the mind by the prescribed method of clearing the passage of the life air is achieved immediately if one fixes his mind directly on the lotus feet of Krsna. The hatha−yoga system, or breathing system, is especially recommended for those who are very absorbed in the concept of bodily existence, but one who can perform the simple process of chanting Hare Krsna can fix the mind more easily... As stated in Bhagavad−gita, one's mind is his enemy, and one's mind is also his friend; its position varies according to the different dealings of the living entity. If we divert our mind to thoughts of material enjoyment, then our mind becomes an enemy, and if we concentrate our mind on the lotus feet of Krsna, then our mind is a friend... In Bhagavad−gita (8.8) it is said that one must practice the breathing exercise (abhyasa−yoga−yuktena). By virtue of these processes of control, the mind cannot wander to external thoughts (cetasa nanya−gamina). Thus one can fix his mind constantly on the Supreme Personality of Godhead and can attain (yati) Him...
This process of purifying the mind is also recommended by Lord Caitanya; He says that one should chant Hare Krsna. He says further, param vijayate: "All glories to Sri Krsna sankirtana!" All glories are given to the chanting of the holy names of Krsna because as soon as one begins this process of chanting, the mind becomes purified. Ceto−darpana−marjanam: [Cc. Antya 20.12] by chanting the holy name of Krsna one is cleansed of the dirt that accumulates in the mind.
¯Srimad−Bhagavatam 3.28.9,10