It is a sacrifice to live life asking God, “What can I do for You today?”
Left on our own, there is no way we can look at our circumstances or Paul look at his wrongful imprisonment and write about joy. But with God, even though Paul was externally in chains, internally he was free and partaking of the joy of the Lord. He was allowing himself to receive the fruit of joy from the Holy Spirit and he was choosing to let it overflow through him despite his present circumstances.
Jesus fixed His eyes not on what was temporary- pain, suffering, agony, shame, rejection, abandonment and separation from His Father but on the joy of having you and I as His.