" ... Before the new birth, sin was clearly our master. Now there's a vastly more powerful rival in the Spirit of God. We have entered a war zone.
The front lines of the war zone are located in our hearts ... Worthless idols never deliver on their promises. God always does. It should be obvious where to set our hearts.
In your daily war against the sin that so easily infects your life, remember to guard your heart. Watch where you set it. Be extremely careful not to let it dwell on impure or unworthy things. Let it be filled with God alone."
excerpt from "Wonder of the Cross devotional" by Chris Tiegreen