From The Penitent Christian 2 by Fr. Francis Hunolt - pages 143-144
… For a true penitent must never cease deploring his sins.
But, you think, if that is the case, one must have a very sad time of it, indeed. There will be no such thing as saying a pleasant word to another, and one’s life must be spent in constant melancholy and sadness; for it appears that we must shut ourselves up and devote our time to weeping and lamentation.
And how, then, can we serve God with child-like confidence and with joyful hearts, as He wishes to be served even by those who have been great sinners? But, my dear brethren, that conclusion is altogether erroneous. You must know that to do penance and be sorry for our sins is not to lead a sad, moping, melancholy life; it is rather to serve God with joy and confidence. Tears of sorrow are bitter in themselves; but what a sweet consolation they leave behind in the heart of the penitent! “ The penitent must always be sorry," says St. Augustine, “and he must always rejoice at his sorrow.” He experiences a true heavenly joy and consolation, of which worldlings know nothing.
Such is the promise made by God to his penitent children in these words: “ Blessed are they that mourn, for they shall be comforted,” not merely hereafter, in the eternal joys of heaven, but they will be comforted also in this life, and they will feel consoled in the midst of, nay, on account of the tears they shed; because their constant sorrow assures them all the more of forgiveness, and they have the testimony of their conscience that they are true children of God, who love their heavenly Father with their whole hearts.
I ask all those who have had experience of this, whether it is not true. What a special relish, and consolation, and joy of heart is caused by shedding copious tears, as it were, through a sensible sorrow for sin! Those who know what it is, desire nothing more than to have that great and tearful sorrow ; and it is only the absence of it that can really trouble them.
From A Practical Commentary on Holy Scriptures by Bishop Frederick Justus Knecht D.D. - pages 469-470
Mourning which is pleasing to God.
There is a great deal of mourning and complaining in this “vale of tears”, but all this mourning is not pleasing to God. When, for example, a man grieves, because his pride or his revenge or any other passion is not gratified, his sadness is the result of sin, and can in no way please God. Our sorrow for the dead, or for personal losses or disappointed hopes, is a holy sorrow only so far as it convinces us of the nothingness of the things of this world, and raises our hearts to God in worship and resignation.
The sorrow most pleasing to God is that of those who renounce the sinful joys of this world, and grieve over their own sins and the sins of others. Examples: Lot, Elias, Jeremias, Judith, John the Baptist.