In plain words
Try to turn this knowledge into divine knowledge. This learning is not lasting. How long will it last? It passes in a moment. Do not waste all your time in learning of this kind and make your life meaningless. In this way, though Śaṅkara had no need of it, he went on doing all his works, every one of them, for the uplift of the world, for the welfare of the world, to give knowledge to the world. Not Śaṅkara alone. Kṛṣṇa too did just the same. What did He say?
For Me, O Pārtha, there is no duty to be done in the three worlds; there is nothing unattained for Me to attain; yet I go on in action.
The Excellence of Karma
There is no work whatever that I have to do in these three worlds. There is no fruit whatever in these three worlds that comes to Me. Yet from dawn until I lie down at night, I go on performing karma. For what? For whom? To what end? For the uplift of the world. When children see their elders, they have the chance to follow them. Others are trying to follow Me and, through that, to cross over. I Myself perform karma. You, too, perform karma. Through this karma alone does your birth find its fulfilment.
“Karmaṇyeva adhikāraste māphaleṣu kadācana.” “Karmānubandhīni manuṣyaloke.” The whole world of men is bound by karma. No one may waste time without doing karma. When I ask many foreigners, “What work are you doing?”, each says, “I am not doing any work.” What does man today take work to mean? They take it to be some job or other, or a business, or some other kind of work. This is not karma. Even our breathing in and breathing out is itself karma. Our eyes are moving. All this is nothing but karma. We are eating. We are putting the hand and the mouth to work. All this is nothing but karma. From the moment it rises at dawn until it lies down at night, this body is engaged in nothing but doing karma. But doing these karmas as worthwhile karmas is the very best.