Because this psalm is so familiar to so many people, it is hard to add to its understanding. Unlike Psalm 22, David was in a place of great calm. He had weathered some storms and was at peace.
People first experience this when they put their faith in Christ, but when problems arise, we tend to revert to our Psalm 22 phase. Satan likes to attack new believers with doubts. He whispers in our ears, “how can you claim to be a Christian when you continue to sin?” Of course, this is a false charge because Christians are not perfect after they believe. Our righteousness is based on faith in Christ’s righteousness to be the sacrifice for our sins. Zechariah 3 is a great illustration of how Christ intercedes for us.
We need the peace that David found. The book of Hebrews chapters 3-5 discusses this issue. It is called entering God’s rest. Originally it was designed for the Israelites who came out of Egypt. But, because of their lack of faith, they failed to find that peace and rest that David describes. What happened was they refused to enter the promise land after about two years at Mt. Sinai. Those who were 20 years old and older when they left Egypt died in the wilderness; the only exceptions were Joshua and Caleb who urged the people to go in and conquer the land. But God wants all His children to enter His rest while on earth.