Since we are living by the Spirit, we should also step by the Spirit, Galatians 5:25

Stepping by the Spirit is when we are carefully paying attention to how we are governing our lives. As we learn new truth from the Scripture, applying them to our lives correctly takes practice. We need to pay closer attention to what we are doing and constantly remind ourselves of the truth and allow our actions to align to it. Those who are more mature in their spiritual lives have the experiential knowledge of how important it is to follow Scripture accurately, especially when under an attack from one of our spiritual enemies. You do not get sloppy when putting up a defense against Satan, the sin nature, or the world system. If you do, you will lose.

In Galatians 5:16 we are instructed that when we walk1 by the Spirit we will in no way fulfill the desires of the flesh, after dealing with the works of the flesh and the fruit belonging to the Spirit, Paul comes back to governing our lives by the Spirit, but points out that there are time when we need to not only look at the big picture (walking), but also smaller details (each step).

As we press on toward the mark, let us who are mature minded step according to the high calling of God. We are now part of the new creation (the Christ). We have been crucified with Christ and raised to walk in newness of life before God. Therefore we are no longer slaves to the sin nature to obey its passions and desires. As we step according to this truth peace – an unruffled mind – and mercy – relief from the results of sin – are upon us.

Philippians 3:14 -16 According to the mark I pursue upon the prize of the high calling of God in Christ Jesus. Therefore as many as are mature, this should be our frame of mind. And if in something we have a different frame of mind, this also our God will make manifest; however, into that which we arrived at, let us step by this same line to frame the mind the same.

Galatians 6:16 and as many as are stepping by this line, peace is upon them and mercy, and upon the Israel of God.
1 Governing the manner of your life. This is not the same word used in verse 25. This has the idea of generally how you go about (walk) through your day.