Catechism of the Catholic Church
All of the above. Para. 2559: "Prayer is the raising of one's mind and heart to God or requesting of good things from God" (St. John Damascene, De fide orth. 3, 24: PG 94, 1089C). But when we pray, do we speak from the height of our pride and will, or "out of the depths" of a humble and contrite heart (Ps 130:1)? He who humbles himself will be exalted (Cf. Lk 18:9-14); humility is the foundation of prayer. Only when we humbly acknowledge that "we do not know how to pray as we ought" (Rom 8:26), are we ready to receive freely the gift of prayer. "Man is a beggar before God" (St. Augustine, Sermo 56, 6, 9: PL 38, 381).
Para. 2563: The heart is the dwelling-place where I am, where I live; according to the Semitic or Biblical expression, the heart is the place "to which I withdraw." The heart is our hidden center, beyond the grasp of our reason and of others; only the Spirit of God can fathom the human heart and know it fully. The heart is the place of decision, deeper than our psychic drives. It is the place of truth, where we choose life or death. It is the place of encounter, because as image of God we live in relation: it is the place of covenant.
Para. 2564: Christian prayer is a covenant relationship between God and man in Christ. It is the action of God and of man, springing forth from both the Holy Spirit and ourselves, wholly directed to the Father, in union with the human will of the Son of God made man.
Para. 2565: In the New Covenant, prayer is the living relationship of the children of God with their Father who is good beyond measure, with his Son Jesus Christ and with the Holy Spirit. The grace of the Kingdom is "the union of the entire holy and royal Trinity . . . with the whole human spirit" (St. Gregory of Nazianzus, Oratio, 16, 9: PG 35, 945). Thus, the life of prayer is the habit of being in the presence of the thrice-holy God and in communion with him. This communion of life is always possible because, through Baptism, we have already been united with Christ (Cf. Rom 6:5). Prayer is Christian insofar as it is communion with Christ and extends throughout the Church, which is his Body. Its dimensions are those of Christ's love (Cf. Eph 3:18-21).