The Thorn In The Flesh

Why does God allow our weakness? For the next few weeks in our devotions, we are going to be taking a look at 2 Corinthians 12 and Paul's struggle with the thorn in his flesh. 
"And He said to me, My grace is sufficient for you, for My strength is made perfect in weakness. Therefore most gladly I will rather boast in my infirmities, that the power of Christ may rest upon me." - 2 Corinthians 12:9