Penance for the sake of penance would have no value; but it can be a helpful means in striving to love God. It is precisely because of this love for God that penance is practiced.
Accept Our Crosses
Is penance really necessary? Our Lord did not equivocate when he spoke of the need for penance, and the Immaculate Virgin entrusted St. Bernadette of Lourdes with the message of penance to be preached to others. But how to do penance? Not everyone’s health and obligations permit them to undertake severe penances, though all admit that crosses are to be found everywhere in life. The acceptance of these crosses in the spirit of penance is a wide field for the practice of penance.
Moreover, the fulfillment of our obligations, the accepting of the will of God at every moment of life and its fulfillment perfectly in action as well as in word and thought, requires a great deal of self-denial, especially of that which would appear to be more pleasant to us. This is indeed the most abundant source of penance.
Drink of the Chalice to its Dregs
In all things let us not forget to repeat with the Lord Jesus: ‘Not my will, but your will be done.’ And if God should judge it appropriate and, as in the Garden, require that we drink the chalice to the dregs, let us not forget that Jesus not only suffered but also rose in glory. So too we go to the glory of resurrection by the way of suffering and the cross.
(From Will to Love: Reflections for Daily Living by St. Maximilian Kolbe, ‘Prophet of the Civilization of Love’.)