Gita Explained
Krishna speaks4.29

अपाने जुह्वति प्राणं प्राणेऽपानं तथापरे ।प्राणापानगती रुद्ध्वा प्राणायामपरायणाः॥

apāne juhvati prāṇaṃ prāṇe ’pānaṃ tathāpareprāṇāpāna-gatī ruddhvā prāṇāyāma-parāyaṇāḥapare niyatāhārāḥ prāṇān prāṇeṣu juhvatisarve ’pyete yajña-vido yajña-kṣapita-kalmaṣāḥ

Word by word
apāne — the incoming breathjuhvati — offerprāṇam — the outgoing breathprāṇe — in the outgoing breathapānam — incoming breathtathā — alsoapare — othersprāṇa — of the outgoing breathapāna — and the incoming breathgatī — movementruddhvā — blockingprāṇa-āyāma — control of breathparāyaṇāḥ — wholly devoted apare—othersniyata — having controlledāhārāḥ — food intakeprāṇān — life-breathsprāṇeṣu — life-energyjuhvati — sacrificesarve — allapi — alsoete — theseyajña-vidaḥ — knowers of sacrificesyajña-kṣapita — being cleansed by performances of sacrificeskalmaṣāḥ — of impurities

The verse says

Others pour the out-breath into the in-breath and the in-breath into the out-breath, stopping the movement of both, given wholly to the control of breath.

In plain words

The most technical verse in the catalogue, and it is about breathing.

Prāṇa going out. Apāna coming in. Pour each into the other, and then hold both still.

This is prāṇāyāma, and it is named here as an offering like any other.

Where you've felt this · in grief

Someone in the worst of it discovers that the only thing they can still govern is how they are breathing. It is not much. On some days it is the entire difference.

Going deeper

Prāṇa and apāna are the outward and inward movements of the life-breath, and the practice described is recognisably the one still taught.

What the Gita does with it is characteristic. It does not explain the technique or claim special results for it. It files it in a list, between giving money away and regulating what you eat.

That placement is a judgement. Breath control was, and is, treated by some schools as the central practice. Here it is one fire among a dozen.

The underlying logic is consistent with everything else in the chapter. Something is being offered rather than kept — in this case the automatic rhythm that runs without you. To offer it is to stop taking it for granted.

And there is a reason breath keeps recurring in these traditions. It is the one process that is both automatic and available, which makes it the natural seam between what happens to you and what you do.