Perfected means to "fill up completely."
So when we battle ourselves, when we try so hard to be strong on our own, when we put so much faith in our own abilities, we are hindering God's power from working through us.
The more of us there is, the less God can work through us.
We either live in such a way that people see us or they see God. I don't think they can see both at the same time. Now, they might not say they see God, but their spirits within will notice. But if all they see is us, they will not be ministered to within.
We can't make God do anything, but we can get out of the way and let Him do whatever He chooses to do.
Those places we struggle, maybe those are the key to where God wants to work most in our lives. Personally, my struggles, the areas of my life that are "weak": finances, my brain function ..... and that brain function is malfunctioning at this moment so I can't think of anything else! But know this, there are a lot of weaknesses in this girl.
Thank God for those weak areas right now (but before you do this I must give one qualifier -- sin isn't a weakness. Sin is sin. If you are a Believer you have power over sin. Sin doesn't need to control you. If there is an area in your life that is very tempted by a certain sin, fall on God and run from that sin. Let God use that area to keep you right with Him).