Summary
Krishna explains that everyone must engage in some sort of activity. He prescribes Karma Yoga, the path of selfless action performed as a sacrifice to the Divine.
Verse 21
यद्यदाचरति श्रेष्ठस्तत्तदेवेतरो जनः । स यत्प्रमाणं कुरुते लोकस्तदनुवर्तते ॥
yad yad ācarati śreṣṭhas tat tad evetaro janaḥ | sa yat pramāṇaṃ kurute lokas tad anuvartate ||
Whatever action a great man performs, common men follow. And whatever standards he sets by exemplary acts, all the world pursues.