One of my teachers told a story about a Mass he went to. The presiding priest introduced the Penitential Rite by inviting the assembly to call to mind their "failures and shortcomings."
At the end of the Mass our teacher went to the priest and told him:
"Paul tells us that we are to boast of our failures and shortcomings, that the power of Christ may shine through us. I came here today for forgiveness of sins."