Many of those who visited Swami Vivekananda found their lives completely changed as a result of their contact with him. Once an old man used to visit him every day, who constantly asked for his blessings and mercy. Accordingly the Swami instructed him in certain practices; but the old man would not follow them. Finally, the Swami became impatient with him. One day, seeing the man coming at a distance, and wishing to be rid of him, he assumed an attitude of extreme reserve. He did not answer any of the old man’s questions; nor did he respond to any of the greetings of the many friends gathered there. They could not understand what the matter with him was. An hour and a half passed in this way, and still the Swami sat like a statue. The old man became angry and left, swearing to himself. The Swami then burst into boyish laughter, in which those present joined. A young man asked, “Swamiji, why were you so hard on that old man?” The Swami replied lovingly, “Dear sons, I am ready to sacrifice my life for you, for you are willing to follow my advice and have the power to do so. But here is a old man who has spent nine-tenth of his life in running after the pleasures of the senses; now he is unfit for both spiritual and worldly life, and thinks he can have God’s mercy for the mere asking! He who is wanting in manliness is full of Tamas [inertia]. It was because Arjuna, the bravest of warriors, was going to lose his manliness that Sri Krishna commanded him to follow the course of life and duty proper to him, so that by fulfilling his duties without attachment to results, he might acquire the Sattvic qualities—purity of heart, renunciation of work, and self-surrender. Be Strong. Be manly. I have respect even for a wicked person so long as he is manly and strong, for his strength will some day make him give up his wickedness, and even renounce all work for selfish ends. It will thus eventually bring him to the Truth.’’

Source: The Life of Swami Vivekananda