“Therefore, having this ministry by the mercy of God, we do not lose heart.”
The Apostle Paul, in 2 Corinthians 4:1, makes it clear that our sustaining grace for service is actually found in the the very message we proclaim. The premise for why we “do not lose heart” is that we have received “this ministry.” Not a vague ministry, but “this” ministry: the gospel ministry. We are to find our joy in the content of our message, not in the context of our ministry. If you define your self-worth by how many people show up to hear you preach, then you have failed to understand the gospel.
Don’t lose heart. You have have received this ministry. Maybe no one will ever respond to your preaching. That doesn’t detract from the gospel one iota. Be strong. Be joyful. You have been entrusted with the mystery of God, the gospel of Jesus Christ.