How do we discover joy?

John 3:26-30 New International Version (NIV) 26 They came to John and said to him, "Rabbi, that man who was with you on the other side of the Jordan—the one you testified about—look, he is baptizing, and everyone is going to him." 27 To this John replied, "A person can receive only what is given them from heaven. 28 You yourselves can testify that I said, 'I am not the Messiah but am sent ahead of him.' 29 The bride belongs to the bridegroom. The friend who attends the bridegroom waits and listens for him, and is full of joy when he hears the bridegroom's voice. That joy is mine, and it is now complete. 30 He must become greater; I must become less."