The theme is found in V.5 : "If I must boast, I will boast in the things which concern my infirmity."
The primary idea is from V.19: "We speak before God in Christ. But [we do] all things, beloved, for you edification."
Golden verse is found in V.10: "Therefore I take pleasure in infirmities, in reproaches, in needs, in persecutions, in distresses, for Christ's sake. For when I am weak, then I am strong."
All scriptures are from the NKJV.