“An awareness of our past failures especially tends to buffet the mind as we pray. Suddenly we feel hopelessly unworthy of offering our petitions.”
From my morning readings in “The Hour That Changes the World”, by Dick Eastman.
So what is important to remember is that grace is a gift. It’s not a one-time gift, that we can mess up, but an ongoing blessing.
That’s not to say that we can sin whenever we want with no effect. But it does mean that if I come to my Father in penitence, He is always ready to hear from me.