How often do we hear the excuse, "Well, I never thought about that!" Or, "I just wasn't thinking." We seem to make and accept these excuses as a normal part of our fallen behavior. And somehow we don't seem to feel we should seek to make a serious change in our ways. But, "thoughtlessness" can be anything but a good excuse! God gave us a brain to think, and to think on things that matter. Too often we stuff our brains with entertainment and meaningless endeavors while starving our brain, and more importantly, our hearts from spiritual food that can give us spiritual strength and wisdom to deal with life.
God's will is what God wants us to do. A Christian would find a far more important activity taking time to read God's Word, fill their minds with the things that God calls important such as the "menu of the mind" in Philippians 4:8, "...Fix your thoughts on what is true, and honorable, and right, and pure, and lovely, and admirable. Think about things that are excellent and worthy of praise." If we would think on those things it would change the way we live! Proof: Proverbs 23:7 NKJV, "For as he thinks in heart, so is he." What your mind dwells on affects the way you will live.
Study God's Word to see what is God's will. A good way to start is to take a good concordance and a good reference Bible and look up passages that speak of the "will of God" and check the cross references. Note 1 Thessalonians 4:3 and 5:18 to start with. Doing right is "thoughtful behavior."