I think it was maybe unclear as to my point last night with the whole prayer and joy thing, as evidenced by my husband’s confused questions :). So to clarify, here’s why I think they are intimately related:
To know who God is and rely on His grace = To rejoice always.
To pray without ceasing = To be constantly reminded of who God is
and my need for His grace.
To pray without ceasing = To rejoice always.