Faith in ourselves: The Bhagavad Gita (4.38) teaches that there is nothing more purifying than Self-Knowledge. So as a first step in gaining purity of mind, we should remind ourselves of our true divine nature, our inherent divine strength. Says Swami Vivekananda: "The remedy for weakness is not brooding over weakness, but thinking of strength. Teach men of the strength that is already within them. Instead of telling them they are sinners, the Vedanta takes the opposite position, and says, 'You are pure and perfect, and what you call sin does not belong to you.' Sins are very low degrees of Self-manifestation; manifest your Self in a high degree." We should look upon God as the whole of Reality, and ourselves as parts of that Reality; God as the divine Fire, and ourselves as sparks of that Fire.
We need to practice thinking about our higher nature and let that thought permeate all our other thoughts and actions. Swami Vivekananda calls this "self-conscious activity." He explains its beneficial effects: "Teach yourselves, teach every one his real nature; call upon the sleeping soul and see how it awakes. Power will come, glory will come, goodness will come, purity will come, and everything that is excellent will come when this sleeping soul is roused to self-conscious activity."
Japa, or repetition of the divine name: God and His name are not different. The more we repeat the divine name, the less will we be able to think worldly thoughts. In Sri Ramakrishna's words, the more we move toward the east, the more the west is left behind. But for japa to be effective, we need to repeat the divine name consciously, with an alert mind. Says Holy Mother Sri Sarada Devi: "Repeating the name of God once, when the mind is controlled, is equivalent to a million repetitions when the mind is away from God. You may repeat the name for the whole day, but if the mind is elsewhere, it does not produce much of a result. The repetition must be accompanied by concentration. Only then does one obtain God's grace." Patience and perseverance will improve the quality of our spiritual practice and help us grow in purity of mind.
For japa to be effective, we should cultivate strong faith in the purifying power of the divine name, and repeat it with yearning and a prayerful attitude. Says Sri Ramakrishna:
"One should have such burning faith in God that one can say: 'What? I have repeated the name of God, and can sin still cling to me? How can I be a sinner any more? How can I be in bondage any more?' "
"God is our Father and Mother. Tell Him, 'O Lord, I have committed sins, but I won't repeat them.' Chant His name and purify your body and mind. Purify your tongue by singing God's holy name."
"There is no doubt about the sanctity of God's name. But can a mere name achieve anything, without the yearning love of the devotee behind it? One should feel great restlessness of soul for the vision of God."
"Chant the name of God, and with it pray to Him that you may have love for Him. Pray to God that your attachment to such transitory things as wealth, name, and creature comforts may become less and less every day."