Confession of Desire
807 Those who by sin have fallen away from the received grace of justification, will again be able to be justified [can. 29] when, roused by God through the sacrament of penance, they by the merit of Christ shall have attended to the recovery of the grace lost. For this manner of justification is the reparation of one fallen, which the holy Fathers * have aptly called a second plank after the shipwreck of lost grace. For on behalf of those who after baptism fall into sin, Christ Jesus instituted the sacrament of penance, when He said: “Receive ye the Holy Ghost; whose sins you shall forgive, they are forgiven them, and whose sins you shall retain, they are retained” [John 20:22, 23]. Hence it must be taught that the repentance of a Christian after his fall is very different from that at his baptism, and that it includes not only a cessation from sins, and a detestation of them, or “a contrite and humble heart” [Ps. 50:19], but also the sacramental confession of the same, at least in desire and to be made in its season, and sacerdotal absolution, as well as satisfaction by fasting, almsgiving, prayers, and other devout exercises of the spiritual life, not indeed for the eternal punishment, which is remitted together with the guilt either by the sacrament or the desire of the sacrament, but for the temporal punishment [can. 30], which (as the Sacred Writings teach) is not always wholly remitted, as is done in baptism, to those who ungrateful to the grace of God which they have received, “have grieved the Holy Spirit” [cf. Eph. 4:30], and have not feared to “violate the temple of God” [1 Cor. 3:17]. Of this repentance it is written: “Be mindful, whence thou art fallen, do penance, and do the first works” [Rev. 2:5], and again: “The sorrow which is according to God, worketh penance steadfast unto salvation” [2 Cor. 7:10], and again: “Do penance” [Matt. 3:2; 4:17], and, “Bring forth fruits worthy of penance” [Matt. 3:8]. (source)
The Dialogue of St. Catherine of Siena: Our Lord speaks about Baptism and Confession of Desire to St. Catherine
Act of Contrition:
O my God, I am heartily sorry for having offended Thee, because I dread the loss of Heaven and the pains of hell, but most of all because I have offended Thee, O my God, Who art all good and worthy of all my love. Therefore I resolve, with the help of thy grace, to confess my sins, to do penance and to amend my life. Amen.
Prayer to make a Spiritual Communion – by St. Alphonsus Liguori
O my Jesus, I believe that Thou art present in the most Blessed Sacrament. I love Thee above all things and I desire to receive Thee into my soul. Since I cannot now receive Thee sacramentally, come at least spiritually into my heart. I embrace Thee as if Thou wert already there, and unite myself wholly to Thee. Never permit me to be separated from Thee. Amen.
“…while he who communicates sacramentally receives without doubt immense grace, both spiritually and corporally, as the Church believes, still, he who abstains from receiving the Body of Christ through obedience and holy discretion, and purely for the glory of God, and who, being inflamed with Divine love, communicates spiritually, merits to receive a benediction like that given to the saint, and obtains from God more abundant fruit, although the order and secret of this conduct is entirely hidden from the eyes of men.”
Our Lord to St. Gertrude