कर्मण्यकर्म यः पश्येदकर्मणि च कर्म यः। स बुद्धिमान् मनुष्येषु स युक्तः कृत्स्नकर्मकृत् ॥

karmaṇyakarma yaḥ paśhyed akarmaṇi cha karma yaḥ sa buddhimān manuṣhyeṣhu sa yuktaḥ kṛitsna-karma-kṛit

He who seeth inaction in action, and action in inaction, he is wise among men, he is harmonious, even while performing all action.

In plain words: Krishna says a truly wise person sees that there can be stillness inside activity, and activity inside stillness. Such a person stays balanced and at peace even while doing all kinds of work.