Ephesians 4:23-24 ESV
and to be renewed in the spirit of your minds, and to put on the new self, created after the likeness of God in true righteousness and holiness.
As Christian, having learn the truth from Christ, we ought to live out the truth. As we learn, the spirit of truth from God will gradually replace our worldly thinking, thus renewing our minds. When our new mind is lived out, we put on a new self. The new self is created according to the teaching of God and the Holy Spirit, so it reflects God's characters which is righteous and holy.
We will not be able to completely put off our old self and put on our new self while in this world and in our weak flesh. Nevertheless, we should strive to align our way to God's teaching, thus live it out. To do so, we need to study the Bible diligently, follow the good models, avoid the pitfalls, and act according to what is taught. The more we live out God's teaching, the more blessed our life become and the more we understand and rejoice in God.