A thought on the first verse: "The Lord, my light and my help."
Is there any significance to these opening words?
Perhaps the Psalmist is capturing the dual nature of man's relationship with God.
On the one hand, we can relate to God, in times of trouble, as the source of help. As a cynical friend of mine once joked: "God, I know you don't exist, but I'm in a spot of trouble here...". When we are in trouble, we instinctively pray.
On the other hand, in times where we might not feel troubled-- when one can focus on spiritual matters -- the Psalmist recalls God as his light.