Jesus warned us to take heed concerning covetousness. In the immediate biblical context (Luke 12:15), someone had just asked Jesus to command that his brother share his inheritance with him. Jesus responds first by saying, "who made me arbitrator over you?" But then He goes on to say, "take heed of covetousness, a person's life does not consist in the abundance of their possessions." St. Paul also tells Timothy that those who desire to be rich fall into temptation and a snare of the devil (1 Tim. 6:9).
Thanksgiving is, in my experience, the best weapon against covetousness. To be thankful for what I have and for what God has done—this is what destroys covetousness. Covetousness is a deadly vine. It can drive the root of bitterness deeply into our hearts if we let it have its way. Covetousness is a deadly vine that grows in the darkness. Thanksgiving is the light that withers away all covetousness and selfishness. When we thank God, we are already obeying Him and so we begin to be filled with light, the light that shifts our focus from outside to inside, from what should be different out there, to Christ dwelling in my heart and the difference Christ makes within me.