The old man watches
All of these lusts and all of this lawlessness we carry around with us in our hearts. The “old man” watches sleeplessly for an opportunity to seize control of the body that it once owned for yet another fling. He is like some sleeping vampire of a horror story. He lies there in his grave, a denizen of the darkness, waiting his chance to seize us by the throat and slake his horrid appetites and thirsts. We must drive the mighty stake of the Cross of Christ through his hellish heart. We must deny him access to our members. We must reckon him dead and remember Calvary. The body is the key to all of this, as we learn from Romans 12:1. Both the ruined life of the “old man” and the regenerate life of the “new man” are expressed through the body. By means of the Cross, God has cut off, positionally, the “old man’s” access to the body. Now we, practically, must reckon this to be indeed so (Rom. 6:11–13).
John Phillips, Exploring Colossians & Philemon: An Expository Commentary, The John Phillips Commentary Series (Kregel Publications; WORDsearch Corp., 2009), Col 3:5.