1182
Śrīmad-Bhāgavatam
[Canto 3, Ch. 28]
two thighs and ankles and sit straight; that posture will help one to concentrate his mind on the Supreme Personality of Godhead. This very process is also recommended in  Bhagavad-gītā , Sixth Chapter. It is further suggested that one sit in a secluded, sanctified spot. The seat should consist of deerskin and  kuśa  grass, topped with cotton.
TEXT 9
प्रणस्य शोधयेन्मार्गं पूर्वम्भकतेचक्रैः । प्रतिकूलेन वा चित्तं यथा स्थिरमचञ्चलम् ॥ ९ ॥
prāṇasya śodhayen mārgaṁ pūra-kumbhaka-recakaiḥ pratikūlena vā cittaṁ yathā sthiram acañcalam
prāṇasya —of vital air;  śodhayet —one should clear;  mārgaṁ —the passage;  pūra-kumbhaka-recakaiḥ —by inhaling, retaining, and exhaling;  pratikūlena —by reversing;  vā —or;  cittaṁ —the mind;  yathā —so that;  sthiram —steady;  acañcalam —free from disturbances.
TRANSLATION
The yogī should clear the passage of vital air by breathing in the following manner: first he should inhale very deeply, then hold the breath in, and finally exhale. Or, reversing the process, the yogī can first exhale, then hold the breath outside, and finally inhale. This is done so that the mind may become steady and free from external disturbances.
PURPORT
These breathing exercises are performed to control the mind and fix it on the Supreme Personality of Godhead.  Sa vai manaḥ kṛṣṇa-padāravindayoḥ : the devotee Ambarīṣa Mahārāja fixed his mind on the lotus feet of Kṛṣṇa twenty-four hours a day. The process of Kṛṣṇa consciousness is to chant Hare Kṛṣṇa and to hear the sound attentively so that the mind is fixed upon the transcendental vibration of Kṛṣṇa's name, which is nondifferent from Kṛṣṇa the personality. The real purpose of controlling the mind by the prescribed method of clearing the passage of the life air is achieved immediately if one fixes his mind directly on the lotus feet of