What experience have you had that gave you unbelievable, unspeakable, joy.  Joy is what motivated the Apostle John to write his letters to congregations in Asia Minor.  But, joy was not the first reaction of the disciples when Jesus met them in the upper room.  Jesus had to "open their minds" for them to "understand" -- then they had unfathomable joy.  What did Jesus do when He opened their minds?  How, only then, were they able to piece it all together?