Fasting is not really something that we naturally like, yet it is something good and even necessary, and as such we should learn how to like it. The following texts may help us and encourage us to fast with a true spirit of penance.
"After fasting forty days and forty nights, He was hungry."
Catechism of the Catholic Church
1434 The interior penance of the Christian can be expressed in many and various ways. Scripture and the Fathers insist above all on three forms, fasting, prayer, and almsgiving, which express conversion in relation to oneself, to God, and to others. Alongside the radical purification brought about by Baptism or martyrdom they cite as means of obtaining forgiveness of sins: effort at reconciliation with one's neighbor, tears of repentance, concern for the salvation of one's neighbor, the intercession of the saints, and the practice of charity "which covers a multitude of sins."
1969 The New Law practices the acts of religion: almsgiving, prayer and fasting, directing them to the "Father who sees in secret," in contrast with the desire to "be seen by men."
2043 The fifth precept (“You shall observe the prescribed days of fasting and abstinence.") ensures the times of ascesis and penance which prepare us for the liturgical feasts; they help us acquire mastery over our instincts and freedom of heart.
N.B: The Code of Canon Law prescribes only two days of penance: Ash Wednesday and Good Friday. Even though there is no canonical obligations to fast on other days, it is not prohibited to fast more. (Christian life is not only doing what is prescribes by the Laws, but is firt a life of union-imitation of Christ) Fasting during Ember Days, Vigil Days and more often during Lent would be a good thing to do - and conform to the old disciplinary traditions of the Church.
Saint Thomas Aquinas
An act is virtuous through being directed by reason to some virtuous good. Now this is consistent with fasting, because fasting is practiced for a threefold purpose. First, in order to bridle the lusts of the flesh, wherefore the Apostle says:"In fasting, in chastity," since fasting is the guardian of chastity. For, according to Jerome: "Venus is cold when Ceres and Bacchus are not there," that is to say, lust is cooled by abstinence in meat and drink. Secondly, we have recourse to fasting in order that the mind may arise more freely to the contemplation of heavenly things: hence it is related of Daniel that he received a revelation from God after fasting for three weeks. Thirdly, in order to satisfy for sins: wherefore it is written (Joel 2:12): "Be converted to Me with all your heart, in fasting and in weeping and in mourning." The same is declared by Augustine in a sermon: "Fasting cleanses the soul, raises the mind, subjects one's flesh to the spirit, renders the heart contrite and humble, scatters the clouds of concupiscence, quenches the fire of lust, kindles the true light of chastity."
First and foremost, clearly, please remember the poor, so that what you withhold from yourselves by living more sparingly, you may deposit in the treasury of heaven. Let the hungry Christ receive what the fasting Christian receives less of. Let the self-denial of one who undertakes it willingly become the support of the one who has nothing. Let the voluntary want of the person who has plenty become the needed plenty of the person in want.
Venerable Louis of Granada
Gluttony urges: God created all these things for us, and he who refuses them despises the benefits of God. Temperance answers: True, God created these things for our maintenance, but He willed that we should use them with moderation, for He has also imposed upon us the duty of sobriety and temperance. It was principally a disregard of these virtues which brought destruction upon the city of Sodom. (Cf. Ezech. 16:49). Therefore, a man, even when enjoying good health, should consult necessity rather than pleasure in the choice of his food. He has perfectly triumphed over this vice who not only limits the quantity of his food, but who denies himself delicacies except when necessity, charity, or politeness prompts him to accept them.
Saint John Mary Vianney
We should gain a great deal for Heaven at our meals; we should deprive ourselves of many little things which, without being hurtful to our body, would be very pleasing to the good God; but we choose rather to satisfy our taste than to please God; we drown, we stifle our soul in wine and food. My children, God will not say to us at the Day of Judgment, "Give Me an account of thy body"; but, "Give Me an account of thy soul; what hast thou done with it?" . . . What shall we answer Him? Do we take as much care of our soul as of our body? O my children! let us no longer live for the pleasure of eating; let us live as the saints have done; let us mortify ourselves as they were mortified. The saints never indulged themselves in the pleasures of good cheer. Their pleasure was to feed on Jesus Christ! Let us follow their footsteps on this earth, and we shall gain the crown which they have in Heaven.
John Henry Cardinal Newman
Fasting is clearly a Christian duty, as Our Savior implies in His Sermon on the Mount. Now what is fasting but a refraining from what is lawful; not merely from what is sinful, but what is innocent? – from that bread which we might lawfully take and eat with thanksgiving, but which at certain times we do not take, in order to deny ourselves. Such is Christian self-denial, - not merely a mortification of what is sinful, but an abstinence even from God’s blessings.