यदि ह्यहं न वर्तेयं जातु कर्मण्यतन्द्रितः।मम वर्त्मानुवर्तन्ते मनुष्याः पार्थ सर्वशः॥
yadi hyahaṃ na varteyaṃ jātu karmaṇyatandritaḥmama vartmānuvartante manuṣyāḥ pārtha sarvaśaḥ
Word by word
The verse says
If I did not keep working, carefully, without slacking — people would follow my path, Arjuna, in every way.
In plain words
The reason he works. Not for himself. Because of what would follow.
And the word atandritaḥ — without slackness, not lazily. It is not enough to act. The manner is being watched too.
Sarvaśaḥ — in every way, completely. People do not copy selectively.
Where you've felt this · in study
A teacher cuts one corner, once, in front of a class. They have taught something that will outlast everything on the syllabus, and it was not on it.
Going deeper
The logic of verse 21 applied to the highest possible case.
If imitation is how standards propagate, then the being at the top of the chain has no private behaviour at all. Every act is a transmission.
Atandritaḥ is the word that repays attention. It rules out a specific cheat: doing the thing, but visibly without care, so that everyone knows your heart is not in it. That would transmit too.
There is a real question a reader can sit with here. Krishna's reason for acting is entirely other-directed. He gains nothing; he works so that the pattern holds. Is that a diminished kind of motive, or the only unmixed one available?
The Gita does not argue the point. It simply presents the highest being in the book doing unnecessary work carefully, because others are watching, and lets the example do the arguing.