Do not conform to the pattern of this world, but be transformed by the renewing of your mind. Paul does not say: Change your behavior. He says: Let your mind be renewed. Transformation begins in thinking.
In the New Covenant the renewal of your mind is the key. Not new rules but a new perspective. When you begin to think as God thinks about you, how you live changes. Naturally, not forced.
Today you can let your thinking be renewed, through truth.