Eucharist and Penance. Daily conversion and penance find their source and nourishment in the Eucharist, for in it is made present the sacrifice of Christ which has reconciled us with God. Through the Eucharist those who live from the life of Christ are fed and strengthened. "It is a remedy to free us from our daily faults and to preserve us from mortal sins."
Source: Catechism of the Catholic Church (Vatican.va)