“Therefore, brethren, we are debtors, not to the flesh, to live after the flesh.”
Romans 8:12

We do not have to live after the flesh, and one way to ensure that your reality is far removed from that is to be deliberate about the contents of your mind- the things you think about:
“For they that are after the flesh do mind the things of the flesh; but they that are after the Spirit the things of the Spirit.” Romans 8:5
He says those who are after the flesh, who seek to satisfy their lusts and desires, mind the things of the flesh- they observe optimistically the things of the flesh.
“If ye then be risen with Christ, seek those things which are above, where Christ sitteth on the right hand of God. Set your affection on things above, not on things on the earth.” Colossians 3:1-2
Instead he instructs us to mind the things of the Spirit, to set our mind on things above and as such live a life that is, far removed from the flesh, yet an absolute expression of God’s pleasure.
“For I know the thoughts that I think toward you, saith the LORD, thoughts of peace, and not of evil, to give you an expected end.” Jeremiah 29:11
“…but to be spiritually minded is life and peace.” Romans 8:6