2 Corinthians 12: Thorn in the Flesh

The Corinthians respected the "super apostles" so much that they paid money (salary?) to them while Paul restrained himself and he didn't charge anything from them. Paul was interested in the hearts of the Corinthians, not their money. Paul was thinking about what made the Corinthians pay so much attention to the super apostles and he begins to brag about spectacular revelations from the Lord, but then, he stops because he understands that:

7-10 Because of the extravagance of those revelations, and so I wouldn’t get a big head, I was given the gift of a handicap to keep me in constant touch with my limitations (the thorn in the flesh). Satan’s angel did his best to get me down; what he in fact did was push me to my knees. No danger then of walking around high and mighty! At first I didn’t think of it as a gift, and begged God to remove it. Three times I did that, and then he told me,
My grace is enough; it’s all you need.
My strength comes into its own in your weakness.

Paul had a thorn in the flesh, a suffering, but he realizes that this suffering made him seek and pray to the Lord. Instead of bragging about his intelligence, etc.; Paul brags about his sufferings because they made him more dependent of the Lord. For Paul, a great man is the one who depends on the Lord.