Here are a few more words from Dallas Willard's "Renovation of the Heart" that I am sinking my teeth into:

"My hope is that this rather lengthy discussion... will make very clear why spiritual formation requires the transformation of the body. The proper retraining and nurturing of the body is absolutely essential to Christlikeness. The body is not just a physical thing. As it matures, it increasingly takes on the quality of 'inner' life. (The body of a small child, by contrast, has almost not inner quality to it, which is why the child can really hide nothing.) That is, the body increasingly becomes a major part of the hidden source from which our life immediately flows.

The outcome of spiritual formation is, indeed, the transformation of the inner reality of the self in such a way that the deeds and words of Jesus become a natural expression of who we are. But it is the nature of the human being that the "inner reality of the self" settles into our body, from which that inner reality then operates in practice. Formed in sin, our character and its body is set against God and God's ways, and as we look about us, we find it running pretty much on its own-- at least for a while.

When our heart (will, spirit) comes to a new life in God, the old "programs" are still running contrary to our new heart, and for the most part they are running in our body and its parts or members. "sin dwells within me... that is, in my flesh" (Romans 7:12-18), even though they are still, "at work in our bodily parts" (Romans 7:5, PAR), even though they no longer can in the long run, "bring forth death." That is because my identity before God has been shifted over to another life that is also now in me as God's gift. While the Spirit is willing by the flesh is weak (Matthew 26:41), I may find myself doing the thing I hate (Romans 7:15). but it really is no longer I who is doing it, but the sin still functioning as a living force in the members of my body (verse 23).

However, this is only a transitional state for those who can say with David, "My soul follows hard after you" (Psalm 63:8). The law or force of the Spirit of life that is in Christ Jesus is now also a real presence in my body and it opens the way to liberation from the force of sin in my bodily parts (Romans 7:23). By not walking in terms of the flesh but in terms of the Spirit, we are increasingly able to do the things that Jesus did and taught (Romans 8:4). We move toward the place where both the spirit is willing and the flesh is strong for God because the Spirit is now occupied by it. We have presented the members of our body "as slaves to righteousness, resulting in sanctification" (Romans 6:19)."

-- Dallas Willard, "Renovation of the Heart," p 165-66