"But He said to me, “My grace is sufficient for you, for My power is made perfect in weakness.” Therefore I will boast all the more gladly about my weaknesses, so that Christ’s power may rest on me. That is why, for Christ’s sake, I delight in weaknesses, in insults, in hardships, in persecutions, in difficulties. For when I am weak, then I am strong." 2 Corinthians 12:9-10
Do you ever think you have to "get it all together" before you can be used for Christ? "One day, when I am really good Christian, know a lot more, or gain more confidence - then God can use me for His kingdom." If these thoughts sound like your own, Satan has you right where he wants you: working for God and trying to do it all on your own.
One of the most prevalent themes of the Bible is God using weak people to magnify His strength. Though on the outside, though each person was weak on their own, they all had one thing in common: belief in God's power. "The LORD does not look at the things people look at. People look at the outward appearance, but the LORD looks at the heart.” 1 Samuel 16:7
Moses was a stutterer when the Lord called him to lead the Israelites in the desert.
Esther was fearful when the Lord called her to save the whole Jewish nation.
Mary was a young teenager when the Lord called her to raise His Son Jesus.
Peter was a people pleaser when he denied Christ - yet God forgave and he became a bold witness for Christ, even unto death.
King's daughter, these people did not have to "get it together" to be powerfully used for God! There is no such thing as self improvement with your loving Father. He is the one who fixes. He is the one who perfects. He is the one who restores. His power is made perfect in your weakness; His grace is sufficient.
Come to Him as you are - no matter your weakness. All He wants is a willing, surrendered heart, ready to be used and expectant of His power to do kingdom works in and through you.