Grace: More Than We Deserve, Greater Than We Imagine by Max Lucado
From the dust jacket:
"Do you worry that you've written too many checks on God's kindness account? Do you drag regrets like a broken bumper? Do you huff and puff more than you delight and rest? If so, then I have a word for you" Max Lucado invites. "Grace".
Lucado's subtitle for the book (More Than We Deserve, Greater Than We Imagine) is a better way to describe this book than I could come up with.