Do not rejoice in this, that the spirits are subject to you, but rather rejoice because your names are written in heaven -Luke 10:20
Jesus Christ is saying here, "Don't rejoice in your successful service for Me, but rejoice because of your right relationship with Me."
The trap you may fall into in Christian work is to rejoice in successful service- rejoicing in the fact that God has used you. Yet you will never be able to measure fully what God will do through you if you have a right-standing relationship with Jesus Christ. If you keep your relationship right with Him, then regardless of your circumstances or whoever you encounter each day, He will continue to pour "rivers of living water" through you (John 7:38). And it is actually by His mercy that He does not let you know it. Once you have the right relationship with God through salvation and sanctification, remember that whatever your circumstances may be, you have been placed in them by God. And God uses the reaction of your life to your circumstances to fulfill His purpose, as long as you continue to "walk in the light as He is in the light" (1 John 1:7).
Our tendency today is to put the emphasis on service. Beware of the people who make their request for help on the basis of someone's usefulness. If you make usefulness the test, then Jesus Christ was the greatest failure who ever lived. For the saint, direction and guidance come from God Himself, not some measure of that saint's usefulness. It is the work that God does through us that counts, not what we do for Him. All that our Lord gives His attention to in a person's life is that person's relationship with God- something of great value to His Father. Jesus is "bringing many sons to glory . . ." (Hebrews 2:10).