2 Corinthians 12

7 even though I have received such wonderful revelations from God. So to keep me from becoming proud, I was given a thorn in my flesh, a messenger from Satan to torment me and keep me from becoming proud.8 Three different times I begged the Lord to take it away. 9 Each time he said, “My grace is all you need. My power works best in weakness.” So now I am glad to boast about my weaknesses, so that the power of Christ can work through me. 10 That’s why I take pleasure in my weaknesses, and in the insults, hardships, persecutions, and troubles that I suffer for Christ. For when I am weak, then I am strong.

well I personally feel as though we all have a thorn in the flesh... and once that one is dug out.. then we get another... and it may be something we lack.. it may be a personality trait.. it may be an illness.. it may be a person... but God gives us all something that challenges us daily... whatever it is.. that is what God uses to change us into what he wants us to be...
14 Now I am coming to you for the third time, and I will not be a burden to you. I don’t want what you have—I want you. After all, children don’t provide for their parents. Rather, parents provide for their children. 15 I will gladly spend myself and all I have for you, even though it seems that the more I love you, the less you love me.

I think that many times.. the more love we show.. the less people love us.. remember when we were young and we used to say that guys only liked a witch.. they didn't want anything to do with a good girl... well I think that is true in our adult life too.. but not only of men.. we all do it... we tend to try so hard to get the ones who do us wrong to love us... instead of accepting the ones that show us love... (there really must be something wrong with us...)
16 Some of you admit I was not a burden to you. But others still think I was sneaky and took advantage of you by trickery. 17 But how? Did any of the men I sent to you take advantage of you? 18 When I urged Titus to visit you and sent our other brother with him, did Titus take advantage of you? No! For we have the same spirit and walk in each other’s steps, doing things the same way.
19 Perhaps you think we’re saying these things just to defend ourselves. No, we tell you this as Christ’s servants, and with God as our witness. Everything we do, dear friends, is to strengthen you. 20 For I am afraid that when I come I won’t like what I find, and you won’t like my response. I am afraid that I will find quarreling, jealousy, anger, selfishness, slander, gossip, arrogance, and disorderly behavior. 21 Yes, I am afraid that when I come again, God will humble me in your presence. And I will be grieved because many of you have not given up your old sins. You have not repented of your impurity, sexual immorality, and eagerness for lustful pleasure.
these are internal sins.. quarreling jealousy anger selfishness slander gossip arrogance... I see some of them in me... sometimes I think if I say an "innocent" comment about someone... it doesn't count.. yet it does... peoples feelings get hurt by our words.. we should be cautious of them... it is easy to say that we have given up impurity sexual immorality and lustful pleasure.. yet if they are in our minds... have we really given them up?? I would say that I am very guilty in my mind of many sins... I need to take some time and purify my mind...