Mike Ratliff at his blog writes:
Therefore, we must understand that we are being called by God to “put to death therefore what is earthly” in us. Why? These earthly things are the very sins that are the reason the wrath of God is coming. How do we kill these things? “ Let not sin therefore reign in your mortal body, to make you obey its passions.” … I used to have the concept of sin “reigning” in me as me sort of coexisting with it, however, that is not a true picture of what Paul is telling us in Romans 6:12. No, either it rules us or Christ does. When sin is king over us then we are in idolatry and that always blinds us spiritually.
In what ways do you put to death what is earthly? How do you crucify the flesh in your quest to “put on the new self” (Eph. 4:24) and follow Christ?