And the mind becomes fit for concentration.

Yogyatā is aptitude, capability, being ready. Prāṇāyāma prepares the mind (manas) for dhāraṇā, concentration.

An agitated mind cannot concentrate; it’s like trying to see the bottom of a lake with waves. Prāṇāyāma calms the waters.

There is an intimate connection between breath and mind. When breath becomes still, thoughts become still. When prāṇa flows smoothly, attention can be sustained.

This sutra marks the transition toward the internal limbs of yoga (antaraṅga). Āsana and prāṇāyāma prepare; now the properly mental work begins.

Pratyāhāra, dhāraṇā, dhyāna, and samādhi are territories of the purified and quieted mind.