God
This Psalm emphasizes God’s existence from the eternal past to the eternal future and contrasts that with how short our lives are in comparison. Verse 8 tells us that God knows even our innermost thoughts. God is so much greater than we are, it can hardly be understood.
We put too much effort into making our short lives more successful and ignoring our eternal relationship with God. Does it make sense to do something to offend God to gain something short-lived in this life? If we lived with eternity in mind, our lives would look very different.