What does 2 Corinthians 4:16 mean?

A main point of this passage is that God uses fragile vessels to carry his powerful truth. Paul, for his part, never pretended to be Superman. He was merely human. All the suffering he experienced truly hurt him. It left scars. He was discouraged at times. For those looking from the outside, he must really have seemed to be wasting away. Perhaps some wondered—and some in Corinth might even have said—"Why are you doing this to yourself? Haven't you done enough? Why not take some time to focus on yourself?"

Paul, though, insists that he is not going to give up. He refuses to lose heart, meaning that he will not give in to the temptation to live in despair. He wants his readers to know that his outward appearance is deceiving. Yes, he is physically wasting away because of his suffering for preaching about Jesus. Inwardly, though, he is being made as good as new every day. He is strong and determined and more convinced than ever of his purpose to carry the light of the gospel to the world.