Jesus was speaking in Jn 4:34. He was expressing His commitment to His God-given assignment. Jesus likened His assignment to the body's commitment to food. Jesus was saying that just like the body cannot be sustained without food, His life was dependent on fulfilling His purpose.
You see if you and I would be just as committed or even more committed to our God-given assignment as our bodies are to food then we will live purposeful lives. This is the challenge that I issue to you today. Make a commitment to live the life that God set you apart for. Be committed to completing your assignment.
Your total commitment to your assignment pleases God - Mt 17:5. And it will be said of you at the end of time that you served your generation - Acts 13:36.