I'm really enjoying A Praying Life by Paul Miller. In a chapter titled Learning to Be Helpless Miller connects the gospel to our prayer life.
Prayer mirrors the gospel. In the gospel, the Father takes us as we are because of Jesus and gives us his gift of salvation. In prayer, the Father receives us as we are because of Jesus and gives us his gift of help. We look at the inadequacy of our praying and give up, thinking something is wrong with us. God looks at the adequacy of his Son and delights in our sloppy, meandering prayers.