[Bhagavad Gita 6.35]

śrī-bhagavān uvāca

asaḿśayaḿ mahā-bāho

mano durnigrahaḿ calam

abhyāsena tu kaunteya

vairāgyeṇa ca gṛhyate

Lord Śrī Kṛṣṇa said: O mighty-armed son of Kuntī, it is undoubtedly very difficult to curb the restless mind, but it is possible by suitable practice and by detachment.

PURPORT

In the present age no one can observe the strict rules and regulations of placing oneself in a sacred place, focusing the mind on the Supersoul, restraining the senses and mind, observing celibacy, remaining alone, etc. By the practice of Kṛṣṇa consciousness, however, one engages in nine types of devotional service to the Lord. The first and foremost of such devotional engagements is hearing about Kṛṣṇa. This is a very powerful transcendental method for purging the mind of all misgivings. The more one hears about Kṛṣṇa, the more one becomes enlightened and detached from everything that draws the mind away from Kṛṣṇa. By detaching the mind from activities not devoted to the Lord, one can very easily learn detachment.

This is practical because by hearing about Kṛṣṇa one becomes automatically attached to the Supreme Spirit. This attachment is called pareśānubhava, spiritual satisfaction. It is just like the feeling of satisfaction a hungry man has for every morsel of food he eats. The more one eats while hungry, the more one feels satisfaction and strength. Similarly, by discharge of devotional service one feels transcendental satisfaction as the mind becomes detached from material objectives. It is something like curing a disease by expert treatment and appropriate diet. Hearing of the transcendental activities of Lord Kṛṣṇa is therefore expert treatment for the mad mind, and eating the foodstuff offered to Kṛṣṇa is the appropriate diet for the suffering patient. This treatment is the process of Kṛṣṇa consciousness.

[Bhagavad Gita 8.8]

abhyāsa-yoga-yuktena

cetasā nānya-gāminā

paramaḿ puruṣaḿ divyaḿ

yāti pārthānucintayan

He who meditates on Me as the Supreme Personality of Godhead, his mind constantly engaged in remembering Me, undeviated from the path, he, O Pārtha, is sure to reach Me.

PURPORT

In this verse Lord Kṛṣṇa stresses the importance of remembering Him. One's memory of Kṛṣṇa is revived by chanting the mahā-mantra, Hare Kṛṣṇa. By this practice of chanting and hearing the sound vibration of the Supreme Lord, one's ear, tongue and mind are engaged. This mystic meditation is very easy to practice, and it helps one attain the Supreme Lord. Puruṣam means enjoyer. Although living entities belong to the marginal energy of the Supreme Lord, they are in material contamination. They think themselves enjoyers, but they are not the supreme enjoyer. Here it is clearly stated that the supreme enjoyer is the Supreme Personality of Godhead in His different manifestations and plenary expansions as Nārāyaṇa, Vāsudeva, etc.

This practice will purify him, and at the end of his life, due to his constant chanting, he will be transferred to the kingdom of God. Yoga practice is meditation on the Supersoul within; similarly, by chanting Hare Kṛṣṇa one fixes his mind always on the Supreme Lord.

- So therefore mind can be contolled by practicing devotional service of which Hearing and Chanting are the most powerful transcendetal methods of purifying one's existence.