Text 57 

cetasa sarva-karmani
mayi sannyasya mat-parah
buddhi-yogam upasritya
mac-cittah satatam bhava 

Translation

In all activities just depend upon Me and work always under My protection. In such devotional service, be fully conscious of Me.

Commentary by Srila Prabhupada

When one acts in Krishna consciousness, he does not act as the master of the world. Just like a servant, one should act fully under the direction of the Supreme Lord. A servant has no individual independence. He acts only on the order of the master. A servant acting on behalf of the supreme master is unaffected by profit and loss. He simply discharges his duty faithfully in terms of the order of the Lord. Now, one may argue that Arjuna was acting under the personal direction of Krishna but when Krishna is not present how should one act? If one acts according to the direction of Krishna in this book, as well as under the guidance of the representative of Krishna, then the result will be the same. The Sanskrit word mat-parah is very important in this verse. It indicates that one has no goal in life save and except acting in Krishna consciousness just to satisfy Krishna. And while working in that way, one should think of Krishna only: “I have been appointed to discharge this particular duty by Krishna.” While acting in such a way, one naturally has to think of Krishna. This is perfect Krishna consciousness. One should, however, note that after doing something whimsically he should not offer the result to the Supreme Lord. That sort of duty is not in the devotional service of Krishna consciousness. One should act according to the order of Krishna. This is a very important point. That order of Krishna comes through disciplic succession from the bona fide spiritual master. 

Therefore the spiritual master’s order should be taken as the prime duty of life. If one gets a bona fide spiritual master and acts according to his direction, then one’s perfection of life in Krishna consciousness is guaranteed.

Commentary by Sri Visvanatha Cakravarti Thakur

"Now, what are you indicating to me particularly? Am I an ananya bhakta? Or am I the sakama bhakta just mentioned by you?"

"You do not have the strength to become the most excellent ananya bhakta. And you should not be the sakama bhakta, the lowest among all the devotees. Therefore, be a madhyama devotee, a devotee intermediate between these two. While offering to me all of your occupational activities and your duties of asrama, you whose goal of life is only to attain me (mat parah), in other words, being niskama, remember me always (mat cittah bhava), even while doing those activities and at any other time also (satatam), being endowed with fixed intelligence, vyavasayatmika buddhi (buddhi yogam upasrtya)."

The Lord has previously said the same:

yat karosi yad asnasi yaj juhosi dadasi yat
yat tapasyasi kaunteya tat kurusva mad-arpanam

Whatever you do, whatever you eat, whatever you sacrifice, whatever you give, whatever austerity you perform, offer it to me, O son of Kunti.    BG 9.27