[Narada Muni to Dhruva]: After sitting on your seat, practice the three kinds of breathing exercises, and thus gradually control the life air, the mind and the senses. Completely free yourself from all material contamination, and with great patience begin to meditate on the Supreme Personality of Godhead.

Purport

In this verse the entire yoga system is described in summary, and special stress is given to the breathing exercises for stopping the disturbing mind. The mind, by nature, is always oscillating, for it is very fickle, but the breathing exercise is meant to control it. This process of controlling the mind might have been very possible in those days millions of years ago when Dhruva Maharaja took to it, but at the present moment the mind has to be fixed directly on the lotus feet of the Lord by the chanting process. By chanting the Hare Krsna mantra one immediately concentrates on the sound vibration and thinks of the lotus feet of the Lord, and very quickly one is elevated to the position of samadhi, or trance. If one goes on chanting the holy names of the Lord, which are not different from the Supreme Personality of Godhead, naturally his mind becomes absorbed in thought of the Lord.

Srimad-Bhagavatam 4.8.44 rendered by Srila Prabhupada