After several verses denouncing the wicked, the psalmist turns to his own heart.
Not only can God see inside us, He understands it. We can trick ourselves into thinking that we’re okay, not really bad, but God is never tricked. He sees the truth.
There is only One way to fix our wrong ways, One way to turn to right. God alone has that power. Righteousness comes through Jesus Christ, and with that righteousness, everlasting life.