In plain words
At the time of doing them he does them joyfully, but afterwards, as the fruit of the karma he has done, he suffers a mountain of sorrow. However small the karma he does, man cannot escape experiencing its fruit. To recognise this truth and act on it is most essential. So before doing any karma, you must enquire into its good and bad. You must not enter into a karma in haste. Haste leads to bad results. That is why the Upaniṣads taught that before doing any karma, man must bow to that karma and then begin it. With this very aim in mind they said, “Tasmai namaḥ karmaṇe”. Why must you bow to karma? You must bow to karma first of all for this alone: that the deity of karma may make you do sacred karmas. You must pray, “O deity of karma! Make me do only sacred karmas, karmas that help others,” and then set about doing the karma. This is the very principle that is the root foundation of the culture of Bhārata. A small example: usually, before dancers begin their dance performance, they touch to their eyes the anklets they tie on their feet, and bow to them. In the same way, players of the tabla and the harmonium too begin to play their instruments only after bowing to them. All in all, the inner meaning of this is that man must first bow to every karma he does, and through that do good deeds and make his birth worthwhile.
From ancient times the culture of Bhārata has given karma a foremost place. To do a karma is easy enough, but to carry the fruit of karma is very hard. The fruit of karma keeps hounding man without a break. So, since you are born a human being, you must take up good deeds. Without good deeds, human life itself turns to waste. Satya alone is morality, Dharma alone is the way, sacrifice alone is glory. Mankind is the very form of these three joined together. The man of today has ruined all three. So humanness itself has sunk out of sight. The doubt arises: is there today such a one as man in the world at all? There must be a close bond and kinship between the thought you think, the word you speak and the deed you do. Such a man alone is called a great soul.