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.