In plain words
The Bhagavad Gītā especially teaches what is called niṣkāma karma as a distinctive path. “Karmaṇy eva adhikārasya”: with these words He said, “You have a right to the karma alone, not to its fruit.” God is the giver of the fruit of karma, not the giver of karma. As the karmas you do, so is the fruit He hands you. If you do no good karmas, in however many ways you pray, God may listen, but He will not come forward to grant those prayers. A small example. In the Mahābhārata, on the day of Sankrānti, Kṛṣṇa was joyfully, merrily holding the rāsa dances; in those days it was the custom, by the tradition of Bhārata, to eat sugarcane. The reason is that it comes in at Sankrānti as the new crop, this sugarcane. Some gopīs offered Kṛṣṇa this sugarcane; Kṛṣṇa was eating it in play; there were no machines in those days, as in modern times, to crush the cane and draw out the juice. As Kṛṣṇa went on eating, the cane cut His little finger and a drop of blood trickled down. Many gopīs, Satyabhāmā, Rukmiṇī, Jāmbavatī: all of them were there. This Satyabhāmā, full of pride at being Kṛṣṇa's wife, sent the gopīs home to fetch cloth. The gopīs were running here and there for cloth. Draupadī, standing close by, tore her sari and, crying “Kṛṣṇa!”, was binding the wound. Well, meanwhile, bandages came, as many as were wanted. Those bandages were of no use to Kṛṣṇa. With that, the day passed. Some time later, the wicked and evil Duryodhana and Duḥśāsana dragged Draupadī into the assembly, to torment her in many ways and to humiliate her. Draupadī, in many ways, to Kṛṣṇa: “Dweller in Dvārakā! Dweller in Gokula! Friend in adversity! Protector of the helpless!” So she went on praying. Kṛṣṇa was hearing all of it. “But to help her in this way, what karma has she done? Has she done any good at all?” He pondered. Has she done before now some karma that would warrant help of this kind? Only then is this help possible. If she has given some help, there is a link for giving help of this kind: so He reflected. That day, on Sankrānti, she had bound His hand with her sari. So now there was a way to give her saris, to give her the fitting fruit. He turned that same little finger. That very sari came without end. So it is karmaṇy eva adhikārasya: we must be masters of our own karmas. Do good karmas, and then God gives a good fruit. So in those days all the gopīs would first bow, saying, “Tasmai namaḥ karmaṇe,” “I bow to the karma I am about to do,” and then do that karma. Why? ‘Even if I bow to God, if what I have done are not good karmas, God too will not bless me. However much service I do, when the karmas are not right, the right fruit does not come. So for all my good and ill, my own karmas alone bring the fruit’: so the gopīs went on bowing to karmas. What kind of karmas are good? That is to say, karmas done for the pleasure of God are good. Karmas that bring God's Prema, karmas that make God gracious.
As Gokak put it, “Bhagawan is the greatest volunteer”; and he said too, “Bhagawan is the greatest Sevadal leader.”