Paul often boasts about the trials and hardships he's endured in service to God, yet he claims that he is not weakened or downtrodden, nor is he led into sin through his weakness and sufferings. I think his point in his rant (11:16-29) is that no one should use their pain or hardships as a crutch or an excuse for backsliding. Paul boasts that he is invigorated by the experience, and we know that this is because the Spirit of the Lord is leading him forward and giving meaning to his trials. Even more, Paul's revelation that came from the thorn in his side (12:7-10) is telling that when we are at our lowest, God is lifted up and uses us as strongholds -- "For when I am weak, then I am strong."

2 Corinthians 11:16-33 and 2 Corinthians 12:7-10