Romans 12:1-2 I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service.  And be not conformed to this world: but be ye transformed [literally: transfigured] by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God.

This word, transformed, is the Greek word, metamorphoo.  From it, we get the English word, metamorphosis.  Metamorphosis is a change from one type of thing into another type of thing.  We apply this word to caterpillars turning into butterflies.

God is very careful about the use of this word in Scripture.  It is only used in three places.  It is used here and it is used in 2 Corinthians 3:18 to explain the same process from a different angle.  Here, Paul explains that we are to take away the veil from our faces (the veil is a reference to the flesh).  He says that, as we behold the glory of the Lord without the veil in front of our faces, we behold the glory of the Lord as in a mirror, and we are transfigured [metamorphoo] into the same image from glory to glory . . . and all of this is performed by the Spirit of the Lord.  Notice that God is telling us the same thing from a different angle.

The other place where this word, metamorphoo, comes up is in the transfiguration of Jesus.  This is the secret coming of Jesus.

Notice also that this is by the renewing of your mind.  Romans 12:1-2 Be Transfigured By The Renewing Of Your Mind

This is in passive voice.  That means that you don't do it.  You are not being told to renew your mind.  Your mind is being renewed.  By whom?  By the Holy Ghost.  This happens as we yield the members of our bodies to the flow of the anointing, the Holy Spirit.