Paul said that he had learned to be content in all circumstances. Paul knew that he could always do whatever it was that God wanted him to do. Because of this reality he was able to be content. Discontent comes when you believe things are out control, when you believe that either you can't do what God wants or you believe doing what God wants doesn't matter. We become discontent when things don't go the way we believe they should. The truth is that even when your children do crazy things, you can know contentment.
Nothing ever gets by God. He is never stressed. His ability to care for you is never in doubt. There is no circumstance in your life that prevents you from honoring God. This means you, like Paul, can always know the peace of contentment.