Prabhupāda: . . . known as saṅkīrtana, Hare Kṛṣṇa Movement. The chanting Hare Kṛṣṇa, you have already heard. Superficially it may appear the repetition of the same word, but every mantra with effect is chanted like that. It requires little practice.
So the effect of this mantra is stated by Lord Caitanya Mahāprabhu: ceto-darpaṇa-mārjanam (CC Antya 20.12). It will cleanse your heart. If you go on chanting this Hare Kṛṣṇa mantra, then gradually the dirty things which are accumulated within our hearts, that will be cleansed. This is the problem.
The dirtiest thing now within our heart is the bodily concept of life. Actually, this is the misconception of whole situation of the modern world. If anyone is in bodily concept of life, that "I am this body," then the basic principle of our life becomes on the false platform, because I am not this body. This is the dirtiest thing within our heart. If you chant Hare Kṛṣṇa mantra, then gradually, by this bhakti-yoga process, we shall understand that, "I am not this body, but I am a spirit soul," ahaṁ brahmāsmi.
There is a Vedic mantra which is called aham: "I, I am Brahman, or the spirit soul." And if we come to that position to understand that "I am not this body; I am spirit soul," then other things will follow, which is stated in this Bhagavad-gītā, brahma-bhūtaḥ prasannātmā na śocati na kāṅkṣati (BG 18.54). When one becomes Brahman-realized, that "I am spirit soul," then the first benefit will be that such person will be free from all kinds of lamentation and hankering.
In this material world two things are going on, lamentation and hankering. Things which we do not possess, we hanker after it, and things we do possess and, somehow or other, we lose, then it is lamenting. So actually the whole situation is lamenting, because we are losing. Take, for example, this body which we have gained from our father and mother on a certain date. It is losing gradually. Suppose you are twenty years old. That means you have already lost twenty years of your total duration of life. Suppose you are to live for hundred years. So twenty years you have already lost, or you have already died up to the amount of twenty years. I am seventy-six years. That means I have also died up to the amount of seventy-six years.
So the age is increasing, that is a false idea. The age is decreasing. Somebody says that, "You are seventy-six years old. Oh, you have so much increased." I am not increased. Practically I have decreased the duration of life.