It is a traditional doctrine of Christian spirituality to embrace repentance and a turning away from sin and back to God. The general law of penance, therefore, is part of the law of God for man.
The Church for her part has specified certain forms of penance, both to ensure that the Catholic will do something, as required by divine law, while making it easy for Catholics to fulfill the obligation.
Thus, all Fridays through the year and the time of Lent are penitential days and times throughout the entire Church.
The abstinence from eating meat or another food is to be observed on Fridays throughout the year unless they are solemnities; abstinence and fast are to be observed on Ash Wednesday and on the Friday of the Passion and Death of Our Lord Jesus Christ.
Those persons who have completed their fourteenth year are bound by the law of abstinence; and all adults from the 18th birthday are bound by the law of fast up to the beginning of their sixtieth year.
Nevertheless, pastors and parents are to see to it that minors who are not bound by the law of fast and abstinence are educated in an authentic sense of penance.
Besides those outside the age limits, others excused from fast and abstinence are those of unsound mind, the sick, the frail, pregnant or nursing women according to need for meat or nourishment, manual laborers according to need, guests at a meal who cannot excuse themselves without giving great offense or causing enmity and other situations of moral or physical impossibility to observe the penitential discipline.
Aside from these minimum penitential requirements Catholics are encouraged to impose some personal penance on themselves at other times.
A person could, for example, multiply the number of days they abstain. Some people give up meat entirely for religious motives (as opposed to those who give it up for health or other motives). Similarly, one could multiply the number of days that one fasted. (10:15)