I despise the "prosperity" "gospel" (I put both words in quotes intentionally...especially "gospel").
"In this world you will have tribulation," declares Jesus. "Consider it all joy when you encounter various trials" says His brother. "Exalt in your tribulation" says Paul. The Word speaks of those who "suffer according to the will of God."
If you aren't in a valley at the moment, you will soon be; or your just got out of one. The key word in Psalm 23 is "through". You go "through" the valley. He goes with you.
And, if you are currently in a valley, perhaps this newer song from Mercy Me will minister grace to you:
MercyMe - The Hurt and The Healer (Official Music Video) from mercymemusic on GodTube.