John never forgot who he was or what his purpose was.

John 1:27-30 New International Version (NIV)
27 He is the one who comes after me, the straps of whose sandals I am not worthy to untie.” 28 This all happened at Bethany on the other side of the Jordan, where John was baptizing. 29 The next day John saw Jesus coming toward him and said, “Look, the Lamb of God, who takes away the sin of the world! 30 This is the one I meant when I said, ‘A man who comes after me has surpassed me because he was before me.’