Hebrews 13:5

"Let your conversation be without covetousness; and be content with such things as ye have: for He hath said, I will never leave thee, nor forsake thee."

St Augustine wrote "we will never find rest until we find rest in thee", psalm 16 says "I have set the LORD always before me: because He is at my right hand, I will not be moved. Therefore my heart is glad, and my glory rejoiceth" and "in your presence is fullness of joy." The more we find our joy and contentment in God the less our outward circumstances will matter to us, the more aware we are of Gods presence with us the less covetous we will be and the more content we will be with what we have.