https://archive.org/details/QuestionsOfMoralTheology

(page 355)

Summary: It’s debated if it’s difficult or not, yet it is encouraged that people attempt to have a perfect contrition for sin.

But either way it is an important theological topic from a Catholic perspective (arguably among the most important):

In attempting to give an answer to this question I presuppose certain doctrines of Catholic faith. I presuppose that contrition is of such efficacy with God that an act of perfect contrition elicited from the motive of God’s infinite goodness at once reconciles the sinner with God. This it does by virtue of perfect charity which contrition implicitly contains. I also presuppose that God seriously desires the salvation of all men, and in His Providence furnishes all with the means to obtain it. The question, then, is not merely one of speculative theology; it is exceedingly practical. For such as cannot receive the sacrament of Penance and yet have committed mortal sin an act of perfect contrition, or of perfect love of God, is the only means of salvation. Thus the question, whether an act of contrition is difficult or not is practically the same as the question whether it is difficult or not for the innumerable multitudes to obtain salvation who, for one reason or another, cannot receive the sacrament of Penance before death.

Catholic encyclopedia on Contrition:

https://www.newadvent.org/cathen/04337a.htm

Catholic teaching distinguishes a twofold hatred of sin; one, perfect contrition, rises from the love of God Who has been grievously offended; the other, imperfect contrition, arises principally from some other motives, such as loss of heaven, fear of hell, the heinousness of sin, etc. (Council of Trent, Sess. XIV, ch. iv de Contritione).

An Act of Contrition

http://www.traditionalcatholic.net/Tradition/Prayer/Act_of_Contrition.html

O my God! I am heartily sorry for having offended Thee; and I detest all my sins, because I dread the loss of heaven and the pains of hell, but most of all because they offend Thee, my God, Who art all good, and deserving of all my love. I firmly resolve, with the help of Thy grace, to confess my sins, to do penance, and to amend my life. Amen.

Related Work: “Contrition: Golden Key of Paradise (1959)” https://ecatholic2000.com/cts/untitled-110.shtml