Another quote from Richard Sibbes (via Mike Reeves):
Often think with thyself, What am I? A poor sinful creature; but I have a righteousness in Christ that answers all. I am weak in myself, but Christ is strong, and I am strong in him. I am foolish in myself, but I am wise in him. What I want in myself I have in him. He is mine, and his righteousness is mine, which is the righteousness of God-man. Being clothed with this, I stand safe against conscience, hell, wrath, and whatsoever. Though I have daily experience of my sins, yet there is more righteousness in Christ, who is mine, and who is the chief of ten thousand, than there is sin in me.