[Romans 8:5 For those who live according to the flesh set their minds on the things of the flesh, but those who live according to the Spirit, the things of the Spirit.]

The human life is a life set and controlled by human senses, the spirit life is a life that is set on and controlled by the Spirit. Romans 8:13 says of we live according to the human senses we shall die. So after salvation God commands us to take a deliberate transformation from the human life to the spirit life.