Therefore, the first requirement for a good liturgical celebration is that both prayer and conversation with God, first listening and then answering. St. Benedict, in his “Rule”, speaking of the prayer of the Psalms, indicates to the monks: mens concordet voci, ”may the mind agrees with the voice.” The Saint teaches that the prayer of the Psalms, the words must precede our mind. Usually it does not happen this way, first one has to think and then what we have thought, is converted into speech. Here, however in the liturgy it is the inverse, the words come first. God gave us the Word and the Sacred Liturgy gives us the words, and we must enter into their meaning, welcome them within us, be in harmony with them. Thus we become children of God, similar to God…

Dear friends, we celebrate and live the liturgy well only if we remain in an attitude of prayer, united to the Mystery of Christ and his dialogue as the Son with the Father. God Himself teaches us to pray, as St. Paul writes (cf. Rom 8:26). He Himself has given us the right words to hear to Him, words that we find in the Psalter, in the great prayers of the liturgy and in the same Eucharistic celebration. We pray to the Lord to be ever more aware of the fact that the liturgy is the action of God and man; prayer that rises from the Holy Spirit and ourselves, wholly directed to the Father, in union with the Son of God made man (cf. Catechism the Catholic Church, n. 2564)

That last paragraph especially addressed the objection of protestants who believe that spontaneous praying “in our own words” is the highest model for prayer. 

The complete text is here.