The word affection in the verse above is the Greek word phronéō. It means to set your mind or your thinking. It originates from the idea of “reining in,” meaning to bring your thoughts under control, and also carries the sense of “fencing in,” or keeping your mind within the boundaries God has set.
Apostle Paul is admonishing us to bring our minds under control. Though your spirit is born again and alive to God, your mind may still have the programming of the old you. That’s why some Christians struggle with addictions, fear, depression, etc.
The Word of God is a more sure word than our experiences. Subject your mind to the Word, and you will give birth to new realities that align with the mind of God. Let the Word of Christ dwell in you richly!