These opponents of Paul had clearly got to him! He is brought to the point where he feels forced to declare his authority as a minister of God. These are the things he has endured in order to preach the Good News - you will find instances throughout the second part of the book of Acts of the Apostles:
going without food
suffering others' ignoring him
Living close to death
Beaten to the point of near death
And through all this, he has proved the mark of the Holy Spirit within him by:
And what has Paul been doing?
Faithfully preaching the Truth
Using spiritual weapons
Serving God whatever peoples' response
Imparting spiritual riches
The reader does, however, get the feeling that Paul loved his life! There must obviously have been times of great suffering and despondency, but God had shown Himself powerful in lots of different circumstances, sometimes intervening directly and other times giving Paul the strength and wisdom to find a way through. 'Yet we have everything!' Paul concludes.