How do you interpret this?

John 3:27 To this John replied, "A person can receive only what is given them from heaven."

John had been called to prepare the way for the Messiah. He had gained quite a following, and had ticked off quite a few as well. I imagine John as loving what he was called to do, a real outdoors kinda guy, full of fire and passion for God. Now things were changing. People were going over to listen to and follow Jesus. John understood this. He understood that this is why he came. He understood that God was in charge. Maybe most importantly, John knew he was not the Messiah.

The Scripture goes on to say that John was even full of joy.

What? How could he be? Didn't he fear the unemployment line? His flock was leaving him. What did his future hold? (I doubt he really understood the full impact of what his future held at this point.)

I believe John understood that God was in control. I think he understood that we get what God gives us, and therefore we live in the moment, and leave the future to God. He understood that it was Jesus who gets the glory.

I need to understand this.