Controlling the prāṇa here, with disciplined movements, when the breath diminishes one should exhale through the nose. The wise one should hold the mind with vigilance, like a chariot drawn by difficult horses.

Prāṇāyāma instructions in an early Upaniṣad:

Prāṇān prapīḍya — controlling, pressing the prāṇa. Implies conscious respiratory regulation.

Saṃyukta-ceṣṭaḥ — with disciplined, united, coordinated movements (ceṣṭa).

Kṣīṇe prāṇe nāsikayā ucchvasīta — when the prāṇa diminishes, one should exhale through the nose. Description of recaka (exhalation) after kumbhaka (retention).

Duṣṭāśva-yuktam iva vāham — like a vehicle drawn by difficult horses (duṣṭa = unruly, difficult). Recalls the chariot metaphor of the Kaṭha Upaniṣad.

Mano dhārayeta apramattaḥ — one should hold the mind with vigilance. Apramatta = without negligence, alert.

This verse is early evidence of prāṇāyāma techniques in the Upaniṣads, centuries before the haṭha yoga texts. The connection between prāṇa control and mind control is already established.