शनैः शनैरुपरमेद् बुद्ध्या धृतिगृहीतया।आत्मसंस्थं मनः कृत्वा न किञ्चिदपि चिन्तयेत्॥
śanaiḥ śanair uparamed buddhyā dhṛti-gṛhītayāātma-sansthaṃ manaḥ kṛtvā na kiñcid api cintayet
Word by word
The verse says
— little by little he should come to rest, with an understanding held firm. Making the mind settle in the self, he should think of nothing at all.
In plain words
Two words carry this verse, and they are the same word twice.
Śanaiḥ śanaiḥ — slowly, slowly.
After all the instruction, the pace being prescribed is gradual.
Where you've felt this · in growing older
Your mother learned to swim at sixty-one, one width at a time, over about a year. There was no morning she could point at as the change. There was a morning she noticed she could swim.
Going deeper
The doubled word is the instruction, and it corrects the rest of the chapter.
Everything before this could be read as a programme to be executed: sit here, hold the spine so, restrain the senses. Śanaiḥ śanaiḥ — slowly, slowly — says the execution is not the point and speed is not available.
That also explains the word for the understanding: dhṛti-gṛhītayā, held by steadiness. Dhṛti is holding-on, endurance, the quality of not letting go. Not force. Grip over time.
And then the last clause, which sounds impossible: he should think of nothing at all. Read beside slowly, slowly, it stops being a demand for instant blankness and becomes a direction of travel.
Which is the more humane reading and the one the next verse confirms, because 6.26 assumes the mind will keep leaving.