The lack of contentment exists when there is a sense of dissatisfaction with life circumstances, people, places, or things. The Greek word for contentment is "arkeo" which means to be satisfied, to have peace of heart and mind, to be at ease on the inside. See the promises related to peace of mind.

Not that I speak from want; for I have learned to be content in whatever circumstances I am. I know how to get along with humble means, and I also know how to live in prosperity; in any and every circumstance I have learned the secret of being filled and going hungry, both of having abundance and suffering need. I can do all things through Him who strengthens me. Philippians 4:11-13