Celebrate, Good Times (and bad). It's a Spiritual Discipline thing!
This Psalm of Thanksgiving shows us how to LIVE in thankfulness toward God, not just feel it.
This Psalm described more than just the innocuous 'feeling' of trusting someone - it describes being actively involved in a trusting relationship with God.
We all wonder "what is going on around here" from time to time.... and we check to make sure that God is near.
Saying "Oh, My God" and meaning it for real - intentionally calling out to God with Joy is what this Psalm is about.