We live in an age when, as Scot McKnight reminds us in his new, provocative book on fasting, many of us look at our bodies to a large extent, as beside the point, while at the same time piling food and drink aplenty in them.
As Scot points out, we westerners have inherited a dualism which fails to see the unity humans are, that the different aspects of us: body, and soul/spirit, are united together in what it is to be human. So when we see spiritual as just about our inner person, we're missing the boat, because spiritual is to pertain to all of us.
When we fail to see this unity in humanity, how part of the real me is my body- just as much as my soul (which essentially just means "life" in Scripture), spirit, or heart, we read in a way inherited from the ancient Greeks, but not the way the Hebrew Bible (Old Testament) or New Testament means. To be sure they are referring to different aspects of our humanity, so that we can divide them that way. But to make up the real us, they need to be seen as united together.
This is why our hope is not in life after death, but as N.T. Wright calls it, "life after, life after death." The resurrection of our bodies in Jesus is our hope, not the intermediate state as wonderful as that will be.
This is important because too often we think we can be holy by being right inside, but being holy also involves what we do with our bodies. Read the book of James with this in mind, which hearkens back to the Old Testament in which what one says and does matters. Our inner and outer self matter before God both in this life, and the life to come.
For me this speaks powerfully in various ways into my daily existence. For example I can't let my body do something (whether eyes, lips, etc.) that in my heart I want to do, if it's not according to God's will. And I know I must deal with the sin in my heart, when this is the case. Same goes on the opposite end: when I have a good thought in my heart, but fail to carry it out with my body, as James would say, "What good is that?"
What might you like to add to these few thoughts?