Grace is defined as "unmerited favor" as well as the love and mercy God freely gives us. Our behavior does not dictate God's love for us; however, because we have God's grace upon our lives we should strive to act well. God, Himself shows us how to act well in Exodus 20:8-10 when He states, "I acted out of who I was, not by how I felt." When we fall short, scripture is clear that in our weakness Christ is strong. In all of God's mercy, He created a system where we truly live under grace. God's grace is sufficient to enable us to act well, and help us rise again when we fall or sin.
II Corinthians 12:9, "But he said to me, "My grace is sufficient for you, for my power is made perfect in weakness." Therefore, I will boast all the more gladly about my weaknesses, so that Christ's power may rest on me."