IV. Let us profit by fasting and good works at this sacred season of the year
Because, then, the Jews, deprived of all the sanctification imparted by these mysteries, turned their light into darkness and their “feasts into mourning,” let us, dearly-beloved, prostrate our bodies and our souls and worship God's Grace, which has been poured out upon all nations, beseeching the merciful Father and the rich Redeemer from day to day to give us His aid and enable us to escape all the dangers of this life. For the crafty tempter is present everywhere, and leaves nothing free from his snares.
Whom, God's mercy helping us, which is stretched out to us amid all dangers, we must ever with steadfast faith resist so that, though he never ceases to assail, he may never succeed in carrying the assault. Let all, dearly-beloved, religiously keep and profit by the fast, and let no excesses mar the benefits of such self-restraint as we have proved convenient both for soul and body. For the things which pertain to sobriety and temperance must be the more diligently observed at this season, that a lasting habit may be contracted from a brief zeal; and whether in works of mercy or in strict self-denial, no hours may be left idle by the faithful, seeing that, as years increase and time glides by, we are bound to increase our store of works, and not squander our opportunities.
And to devout wills and religious souls God's Mercy will be granted, that He may enable us to obtain that which He enabled us to desire, Who lives and reigns with our Lord Jesus Christ His Son, and with the Holy Ghost, for ever and ever. Amen.
Source: Sermons (New Advent)