St. Augustine says that “whole Christ” [totus Christus] prays the psalms. He explained, "By whole I mean with His body, of which He is the Head.” Head and body are Christ and the church. The two are united in one voice and inseparable.
In the Psalms, and not merely Psalms of praise, or general petition, but even (and especially) those on the brink of despair while alienated from God; they’re all on the lips of Jesus. He speaks for us, with us, as one with us. St. Augustine teaches us to pray the Psalms as those caught up in Jesus’ prayer and He in ours. The cross and resurrection are the life of the whole Christ; what goes for Jesus goes also for His Body, the church. This means that in our loneliness, abandonment, suffering, and even death, Christ is there with us and we are with Him, and we are in solidarity with each other.
With the Psalms, then, David prays, we pray, but above all — and with all of us together — Jesus prays. St. Pope John Paul II often repeated a quote from Vatican II that in his incarnation Christ identified with each one of us in a personal way. While on earth, Jesus prayed the Psalm with his parents at home, in the synagogue, and with his disciples. When we pray(sing) the psalms, Jesus is praying with us. When we sing any of the psalms we should imagine Christ leading us in the Psalm.
Psalm 145 is a joy-filled psalm that extols, blesses, praises, meditates on, and enumerates many of God’s divine attributes, his works, and his kingdom.