What anyone else dares to boast about - I am speaking as a fool - I also dare to boast about. Are they Hebrews? So am I. Are they Israelites? So am I. Are they Abraham's descendants? So am I. Are they servants of Christ? (I am out of my mind to talk like this.) I am more. I have worked much harder, been in prison more frequently, been flogged more severely, and been exposed to death again and again. Five times I received from the Jews the 40 lashes minus one. Three times I was beaten with rods, once I was stoned, three times I was shipwrecked, I spent a night and a day in the open sea, I have been constantly on the move. I have been in danger from rivers, in danger from bandits, in danger from my own countrymen, in danger at sea; and in danger from false brothers. I have labored and toiled and have often gone without sleep; I have known hunger and thirst and have often gone without food; I have been cold and naked. Besides everything else, I face daily the pressure of my concern for all the churches. Who is weak, and I do not feel weak? Who is led into sin, and I do not inwardly burn?
If I must boast, I will boast of the things that show my weakness. The God and Father of the Lord Jesus, who is to be praised forever, knows that I am not lying."
Paul boasts about his sufferings
It is hard to believe that Paul endured such physical punishment and still lived to proclaim God's word another day, he was NOT deterred from his mission. Truly God had a purpose for his life and Paul was willing to endure anything by the power of the spirit to continue to spread the gospel.
Paul was angry that false teachers who had impressed and deceived the Corinthians, therefore, he had to reestablish his credibility by listing the trials he had suffered in his service for Christ.
Paul was literally sacrificing his life for the gospel, something the false teachers would never do. The trials and hurts we experience for Christ's sake build our character, demonstrate our faith, and prepare us for further service to the Lord.