Bhagavad Gita 3.21 · BG 3.21
Chapter 3Verse 21
Karma Yoga
यद्यदाचरति श्रेष्ठस्तत्तदेवेतरो जनः। स यत्प्रमाणं कुरुते लोकस्तदनुवर्तते॥
yad yad ācarati śreṣṭhas tat tad evetaro janaḥ, sa yat pramāṇaṁ kurute lokas tad anuvartate
Translation
Whatever action a great person performs, others follow. Whatever standard they set, the world pursues.
Lead by example. The world follows what you do, not what you say.
What does this mean?
People learn far more from what you do than from what you say, a reason to hold your own actions to the standard you'd want reflected back.
In simple words
Krishna points out that whatever a respected person does, others copy, and whatever standard they set becomes the standard everyone follows. People learn from what you do far more than from what you tell them.
The deeper idea
The verse is about influence through example, and it's aimed particularly at people in visible positions. The claim is that behavior propagates: your actions set a reference point that others quietly calibrate to, whether or not you intended to lead. That raises the stakes on private conduct, because it isn't really private if people can see it. The implied instruction is to hold your own actions to the standard you'd actually want reflected back through everyone watching.
How it applies to life
A manager who says the right things about work-life balance and then emails at midnight has set the real policy, and it isn't the one in the handbook. Kids absorb how their parents handle frustration, not the lecture about patience. If you're in any position where people watch you, the useful question isn't what you're telling them to do. It's what you're modeling, because that's what actually spreads.