I rather wonder if we Americans should hear this regularly. From a purely physical perspective, I think most of us could stand to be chiseled out a bit more. I look at myself in the mirror and think "I think there's a smaller me in there somewhere, if I could take that piece off and that piece off, and maybe that one ..." I don't know that Rob was necessarily talking about that when he wrote the book, but you never know.
What I think he was getting at was that we as people are works of art in progress, that we as human beings need to let the master artist work on us, transform us, and that involves some pain. Transformation is not easy; it means going through the pain of having our addictions and preferences and time-worn habits ripped away from us, piece by piece, and replaced with ... what? I think it's at this point that I've heard teachers forget that the phrase "God fills that void" isn't necessarily that helpful, even if it is true. God still has to fill it with something, and it's a choice on our part to let him carve out a new picture for our lives. It's all dependent on our willingness to let those holes remain open for God to fill, and not ourselves fill them with the old habits or new albeit broken ones. If we let Him do His transforming work - a process that is by no means instantaneous - God begins stripping away our addictions and bad habits, and then replaces them with new habits, new practices. Where once there were habits of financial debt, God replaces with habits of responsible generosity. Where there was once an adulterer, God replaces with habits of loyalty and interdependence. Where there was once a drug addiction, God replaces with habits of service and hospitality.
If we'll let him.