Discontent is a sin that is its own punishment and makes men torment themselves; it makes the spirit sad, the body sick, and all the enjoyments sour; it is the heaviness of the heart and the rottenness of the bones. It is a sin that is its own parent. It arises not from the condition, but from the mind. As we find Paul contented in a prison, so Ahab discontent in a palace. Matthew Henry's Commentary on the Whole Bible (McLean, Mac Donald Publishing Company) 694

This is God's universal purpose for all Christian suffering: more contentment in God and less satisfaction in the world.

If I find in myself a desire which no experience in this world can satisfy, the most probable explanation is that I was made for another world.

God is most glorified in us, when we are most satisfied in Him.