Kṛṣṇa consciousness is very simple. Simply chant these sixteen words: Hare Kṛṣṇa, Hare Kṛṣṇa, Kṛṣṇa Kṛṣṇa, Hare Hare/ Hare Rama, Hare Rama, Rama Rama, Hare Hare. If we take to chanting this mantra, we come directly in touch with the Supreme Lord. That makes us purified. If we go near the fire we become warm. Similarly, if we come directly in touch with the Supreme Spirit, our purification begins. So if you chant this Hare Kṛṣṇa, Hare Kṛṣṇa, your impure consciousness will be purified and you will know what you are. Chanting Hare Kṛṣṇa is the process of cleansing the mind of all dirty things. And as soon as you are cleansed of all dirty things, your material anxieties are over. That is stated in the Bhagavad-gita [18.54]
Brahma-butah prasannatma na socati na kanksati
Samah sarvesu bhutesu mad-bhaktim labhate param
The word brahma-bhuta [SB 4.30.20] means that as soon as you come to the platform of spiritual understanding, you immediately become joyful and are freed from all material anxieties. You no longer hanker after any profit, nor are you very sorry when there is a great loss (na socati na kanksati). Then you can see everyone on an equal level, and your lost relationship with the Supreme Personality of Godhead is again established. Then your real life begins.
Lord Caitanya Mahaprabhu prescribes the chanting of Hare Kṛṣṇa. As soon as our heart is cleansed by chanting this Hare Kṛṣṇa mantra, the blazing fire of our problematic material existence is extinguished. How is it extinguished? When we cleanse our heart we will realize that we do not belong to this material world. Because people are identifying with this material world, they are thinking, “I am an Indian, I am an Englishman, I am this, I am that.” But if one chants the Hare Kṛṣṇa mantra, he will realize that he is not this material body. “I do not belong to this material body or this material world. I am a spirit soul, part and parcel of the Supreme. I am eternally related with Him, and I have nothing to do with the material world.” This is called liberation, knowledge. If I don’t have anything to do with this material world, then I am liberated. And that knowledge is called brahma-bhuta. Therefore those who are Kṛṣṇa conscious devotees have taken shelter of Kṛṣṇa, and the beginning is hearing and chanting. Sravanam kirtanam visnoh.
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “The Quest for Enlightenment”, Page 11
A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “The Science of Self-Realization”, Page 166 and 167