Raised in the Catholic Church, I learned that penance was a litany of prayers assigned by a priest to atone for "sins" that were confessed, whether you were age 6 or 60. But I later discovered that engaging in penance is a rather common human behavior, triggered by guilt.
Indeed, penance is an act of self-punishment for real or perceived wrongdoing. This may be due to failed relationships (usually with a family member, lover or close friend), hidden affairs, mistreatment of colleagues or other similar behavior. Penance may come in the form of excessive exercise, compulsive good deeds, a decision to forego rewarding and pleasurable activities or the choice to withdrawal from established social circles.
Unfortunately, the self-imposed penance rarely erases the underlying guilt and counseling is likely to be far more effective for penitents. Convincing oneself of that fact, however, is difficult at best.
See also: Guilt