David spent much of his youth in the fields taking care of sheep. He led them through mountain valleys to find luscious green pastures. He made sure they had plenty of water. He protected them from wild animals. When a sheep strayed, he found it and brought it back to the safety of the flock. David knew what it meant to be a shepherd. Later in his life, when he became king of Israel, he reflected on the living God and wrote this psalm.