
By lessening the tendency for restlessness and by meditating on the infinite, posture is mastered.
Yoga Sutra 1.35
विषयवती वा प्रवृत्तिरुत्पन्ना मनसः स्थितिनिबन्धिनी॥३५॥
Coming into activity of higher senses also becomes helpful in establishing steadiness of the mind.