Another passage which sits tightly alongside Romans 12 is found near the start of the letter to the Philippians:
This is my prayer: that your love may abound more and more, with knowledge and all discernment, so that you can figure out properly things that differ from one another, so that you may be blameless and innocent for the day of the Messiah, filled with the fruits of righteousness which come through Jesus the Messiah to the glory and praise of God. (1:9-11)
The part I have put in italics show how the same theme works out. Thinking of and praying for his beloved people in Philippi, Paul wants them, of course, to grow in love; but this love is not a matter of "undisciplined squads of emotion," but a thought-out habit of the heart -- the heart knowing why it approves what it approves and why it disapproves what it disapproves.
...Part of the problem in contemporary Christianity, I believe, is that talk about the freedom of the Spirit, about the grace which sweeps us off our feet and heals and transforms our lives, has been taken over surreptitiously by a kind of low-grade romanticism, colluding with an anti-intellectual streak in our culture, generating the assumption that the more spiritual you are, the less you need to think.
I cannot stress too strongly that this is a mistake. The more genuinely spiritual you are, according to Romans 12 and Philippians 1, the more clearly and accurately and carefully you will think, particularly about what the completed goal of your Christian journey will be and hence what steps you should be taking, what habits you should be acquiring, as part of the journey toward that goal, right now.1
1. N.T. Wright, After You Believe: Why Christian Character Matters [Harper One: New York, NY; 2010] pp. 157-158