पूरकादिनिजायामादृढाभ्यासादखेदजात् ।एकान्तध्यानसंयोगात्प्राणस्पन्दो निरुद्ध्यते
In plain words
From one's own regulation of the breath beginning with pūraka; from firm practice, undertaken without strain; from union with one-pointed meditation -- the vibration of prāṇa is restrained.