One of Paul's recurring themes throughout 2 Corinthians is that God's strength is made perfect in weakness. In 1 Corinthians, he emphasizes that the strength, wisdom, and power of God are shown in what is normally a sign of weakness and humiliation — the Cross (1 Corinthians 1:18-2:5). Paul wasn't a wimp — remember all that he endured and kept on serving the Lord (2 Corinthians 11:24-27). He just knew that even with all his training and talent, he wasn't skilled, smart, or strong enough to do all that needed to be done for the Kingdom of God. But he knew that when we recognize our insufficiency, God takes our weakness and uses it powerfully when we offer ourselves to him!