The following extract is from The Indwelling Life of Christ by Ian Thomas
The human spirit is that part of us where God lives within us in the person of the Holy Spirit, so that with our moral consent (and never without it), God gains access to our human soul. This is where He Himself, as the Creator within the creature, can teach our minds, control our emotions, and direct our wills, so that He, as God from within, governs our behavior as we let God be God.
“If we live in the Spirit, let us also walk in the Spirit” (Galatians 5:25), and this is what it means to walk in the Holy Spirit: to take one step at a time, and for every new situation into which every new step takes you, no matter what it may be, to hear Christ saying to your heart, “I AM,” then to look up into His face by faith and say, “You are! That is all I need to know, Lord, and I thank You, for You are never less than adequate.”
The LORD is the strength of my life. (Psalm 27:1)