"So to keep me from becoming conceited because of the surpassing greatness of the revelations, a thorn was given me in the flesh, a messenger of Satan to harass me, to keep me from becoming conceited." ~ 2 Corinthians 12:7
Whether it was a physical thorn (eye problems, leukemia, or bad gout from always being on the go) or a "thorny" person or group of people bent on belittling and persecuting Paul at every turn (more likely), Paul was under attack.
His physical stamina was at risk of being depleted.
His emotional fortitude was growing weak.
And his spiritual resolve was under direct assault.
What could he do? What should he do? Why was this happening to him?
Paul prayed.
In fact, he pleaded and begged God to remove the problem and the pain.
And God's answer was "No. I have a greater purpose in keeping you completely dependent upon Me while you undertake the mission for which I have sent you out."
The Holy Spirit served Paul in his agony and Paul's response was what we are all called to who say that we are following Christ Jesus by faith: Trusting in the strength of the LORD instead of our own strength. Seeing God's strength perfected in our weakness. Staying humble under the Shepherd's caring hands and watchfulness as He leads us forward.