Much of our lives as believers is lived between the two points of 'promise' and 'fulfillment'.  We know God is there and that he cares for us and that he'll one day come through on all his promises to us.  But it hasn't happened yet.  We're waiting... and waiting.  And while we wait, what are we supposed to do?  How can we learn to wait well?  This psalm is for all who have ever found themselves situated in a place of waiting for God to act.