One preacher said, "There is too much in this Psalm for a thousand pens to write."
Twice at the beginning an four times at the end we are met with its purpose - "Bless the Lord." There are no requests made in this Psalm; it is pure praise.
The Psalmist quickly deals with the universal problems of sin, sickness, and death by proclaiming God's forgiveness, healing, and redemption. In nearly every verse we read of God's mercy and fatherly affection for His children.