Catechism of the Catholic Church §2784 — excerpt
The free gift of adoption requires on our part continual conversion and new life. Praying to our Father should develop in us two fundamental dispositions: First, the desire to become like him: though created in his image, we are restored to his likeness by grace; and we must respond to this grace.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: St. Cyprian, De Dom. orat. 11 PL 4:526B · St. John Chrysostom, De orat Dom. 3: PG 51, 44 · St. Gregory of Nyssa, De orat. Dom. 2: PG 44, 1148B