"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."
From Walking With God (p. 115):
"When your mind is renewed, you are fine-tuned to God's channel for communicating with you and discovering His will for your life."
Romans 12:2 is nothing short of profound. If we "renew our minds" we will be "transformed" and then can "test and approve" God's will for our lives - which will be good, pleasing, and perfect.
How do we renew our minds? Spend time in prayer, in meditation, in God's word. Feed your mind with spiritual nourishment. This is an area in which Christianity and science merge. Studies show that mindfulness meditation and keeping our brains active through use (reading, learning, analysis - applying your cognitive abilities in an active manner) actually reverses aging of the brain, increases grey matter, and enhances cognitive abilities. When our focus is solidly on the Scriptures, when we are fully cognizant of the indwelling Holy Spirit, and when we draw close to God, we renew our minds spiritually. I use walking as my method of renewal. Each of us will find his or her own ideal way to generate renewal. The key is to find your way and do it daily.
What happens then? Paul says we will be transformed. This "consequence" is even more powerful when we understand that the word used here is the same word used in describing the transfiguration of Jesus (source: NIV Study Bible footnote). See Matthew 17:1-8. Wow. Notice, too, when Jesus was transfigured, God spoke to the disciples (Peter, James, and John) ("This is my Son, whom I love; with him I am well pleased. Listen to him!")
Can you imagine God saying the same thing about you? When you become a "living sacrifice," when you renew your mind (and no longer conform to the "pattern of the world"), you are transformed and are in tune with God's will, which is pleasing to Him. So . . . God is saying the same thing about you! You are his child. He loves you. He is pleased with you. Double wow.
All we need do is turn on the spiritual radio. So often we forget to do that. God's signal - His voice - is already there, but if the radio isn't on and tuned in, we won't hear it. Turn on God's radio daily. Experience renewal . . . and transformation. Your life will be aligned with God's will. It will be good, pleasing, and perfect.