Gal 4:13-16 You know that because of physical infirmity I preached the gospel to you at the first. 14 And my trial which was in my flesh you did not despise or reject, but you received me as an angel of God, even as Christ Jesus. 15 What then was the blessing you enjoyed? For I bear you witness that, if possible, you would have plucked out your own eyes and given them to me.
When Paul initially came to the region of Galatia he was not planning on staying, but due to a chronic illness he had no other choice accept to stay. Paul's sick room became his pulpit. He calls his sickness a "trial in his flesh." It seems that his illness had something to do with his eyes.
In writing to the Corinthians Paul referred to an ongoing physical illness as a "thorn in the flesh." 2 Corinthians 12:7-9. He said that it was used as a buffeting tool from Satan to keep him humble. Paul pleaded three times with the Lord to heal him, but he was not healed. However the Lord responded to Paul's request and said, "My grace is sufficient for you, for My strength is made perfect in weakness." 2 Cor.12:9 For Paul being in the ministry came with some pain attached to it. Yet this pain that God allowed kept Paul humble and useful for the kingdom of God. Paul came to a place where he learned to accept what God allowed. He even came to the place that he took pleasure in his difficulties for he discovered a strength and a grace he had never known before.
Perhaps you are in a place of experiencing some pain. You have pleaded with the Lord to change the circumstances and it has not happened yet. There is a grace that God will provide in all your weaknesses. His grace will be sufficient and His strength will be enough to sustain you. "We can ignore even pleasure. But pain insists upon being attended to. God whispers to us in our pleasures, speaks in our conscience, but shouts in our pains, it is His megaphone to rouse a deaf world."- C.S. Lewis