In the "Teaching Tips" for this lesson, Greg Blake notes:

Church discipline is always open to abuse, so Paul left some principles for the Galatians to follow:
The task is not that of punishment but of restoration; (more…)

In the "Biblical Perspective" notes on this verse, Dr. Marsh Jones writes:

The apostle used a metaphor to explain the behavior of a Christian. (more…)

In the Teaching Tips for this coming Sunday's lesson, Greg Blake writes:

The flesh and the Spirit are used here by Paul to talk about two regimes or domains, if you will. Life in the Spirit, or according to the Spirit, is a life where the Spirit is in control and has come to reside with the individual who has accepted God’s gift of eternal life in Christ Jesus. To “walk by the Spirit” entails a genuine decision. However, this is not a decision involving a strong effort of the will to overcome enormous obstacles in order to get something accomplished. Rather, Christians are called to entrust themselves to the Spirit, to God’s activity, and simply to follow His guidance. It is just the opposite of all the characteristics of life, or existence, accord- ing to the flesh, which will eventuate in death.

Lesson 5: "Flesh Vs. Spirit", Galatians and Ephesians, Adult Teacher's Insights, p. 29.

Dr. Marsh Wilkinson Jr, in his comments on this verse, writes:

The first part of this verse may be understood to mean a number of things, all of them plausible and not necessarily exclusive: (1) I am convinced that nothing but the blood of Christ can save me, and thus I have given up on the law and its system; (2) I am so dead to the world with its affections and lusts that it is as though I have been crucified with Christ; (3) I am one with Christ, and my will is completely His. Paul stated that he was not literally dead, yet he was not the same person that he once was, either. He had taken on Christ completely so that he had totally died to his own will and made the will of God one with his. He was still in the flesh, and yet he was living by faith and obtaining victory over sin. How did he do it? By the power of Jesus Christ, who loved him and died for his sins.

From Lesson 5: "Flesh vs. Spirit", Galatians and Ephesians, Adult Teacher's Insights, July 5, 2015.

Dr. Marsh Jones writes concerning Galatians 5:14 ...

The entire law, all that is expected of us in respect to our fellow man, is contained in this one phrase. If we love our neighbors as much as we love ourselves, then we are naturally loving and serving God, for only He could provide the grace to fulfill such an all-encompassing task. This is a very high standard indeed, but one which God can and will give us the power to accomplish if we live in His will and serve Him in love.

From "Biblical Perspective", Galatians and Ephesians, Adult Teacher's Insights, p. 25.