In Romans 12:2, Paul tells us, "Do not conform any longer to the pattern of this world, but be transformed by the renewing of your mind. Then you will be able to test and approve what God's will is–his good, pleasing and perfect will." (NIV) God develops us into Christlikeness by transforming our wills, minds, and behaviors to conform to His will. Philippians 2:13, “For it is God who worketh in you both to will and to do his good pleasure.” This does not mean we will be perfected in our fallen flesh, which is an impossibility, but the intention, will or endeavor of the heart will be to do His will.
"I never lose heart; though my outward man decay, my inner man is renewed day after day. The slight trouble of the passing hour results in a solid glory past all comparison, for those of us whose eyes are on the unseen, not on the seen; for the seen is transient, the unseen is eternal."
II Corinthians 4:16, 17 (Moffatt)