न हि कश्िचत्क्षणमपि जातु तिष्ठत्यकर्मकृत्। कार्यते ह्यवशः कर्म सर्वः प्रकृतिजैर्गुणैः ॥

na hi kaśhchit kṣhaṇam api jātu tiṣhṭhatyakarma-kṛit kāryate hyavaśhaḥ karma sarvaḥ prakṛiti-jair guṇaiḥ

Nor can anyone, even for an instant, remain really actionless; for helplessly is everyone driven to action by the qualities born of nature.

In plain words: Krishna says no one can stop acting, not even for a moment. Everyone is pushed to do things by the natural forces inside them.