"Sheep are so easily frightened that if a cool stream bubbles and splashes too much, they will not approach to get life-giving water because they’re afraid of the sound. That’s why a good shepherd will often dam up a stream and create a pool or a quiet place where the flock will not be afraid to get a drink...Three key areas of personal need underlie David’s words: physical, emotional, and spiritual. He reminds us that the Almighty God of the universe is committed to meeting our physical, emotional, and spiritual needs. When David wrote, “He makes me lie down in green pastures,” he knew that sheep don’t look for the best grass on their own. The shepherd makes them go to fields where their physical needs can be met. Likewise, God will take you to places where you will be physically nourished. When David says, “He leads me beside quiet waters,” he speaks of taking care of the sheep’s physical needs. Sheep will not lie down in grass, graze freely, or drink from the still waters if there is friction within the flock, danger lurking outside of the flock, or parasites within their bodies. In other words, their physical needs have to be met before they can lie down...Sometimes God will answer in miraculous ways. Sometimes, however, God will take us through situations we never would choose for ourselves and allow us to deal with dangerous times of following him through “the valley of the shadow of death.” Whatever the circumstances, we can experience God’s provision, protection, and guidance. He promises to lead us to a place where there are green pastures and quiet waters."
I also found this encouraging:
"We learn this from David’s declaration, “I will fear no evil.” Fearless living is a choice. God is willing to see us through,but we have to be strong and courageous to continue following him through those valleys. Courage is not the absence of fear. Courage is trusting God and his Word even when circumstances seem impossible. Memorize Isaiah 40:31, and say it often when you feel fear’s grip upon your soul:
But those who hope in the LORD will renew their strength.
They will soar on wings like eagles; they will run and not grow weary,
they will walk and not be faint."--Finding God When You Need Him Most, by Chip Ingram.