Reading Romans 8:9 KJV - But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his.
NASB - However, you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. But if anyone does not have the Spirit of Christ, he does not belong to Him.
Notice how it says you ARE NOT IN THE FLESH! It’s doesn’t say when you’re confused or have issues deciding make sure you walk in the Spirit. It tells you straight up, Hey YOU! You ARE NOT IN THE FLESH, You ARE in the Spirit!
Paul is telling you your identity here. You ARE NOT the old man, YOU ARE the new man.