I have set the Lord always before me - By night as well as by day; in my private meditations as well as in my public professions. I have regarded myself always as in the presence of God; I have endeavored always to feel that, his eye was upon me. This, too, is one of the certain characteristics of piety, that we always feel that we are in the presence of God, and that we always act as if his eye were upon us. Compare the notes at Acts 2:25.

Because he is at my right hand - The right hand was regarded as the post of honor and dignity, but it is also mentioned as a position of defense or protection. To have one at our right hand is to have one near us who can defend us. Thus, in Psalm 109:31, "He shall stand at the right hand of the poor, to save him," etc. So Psalm 110:5, "The Lord at thy right hand shall strike through kings in the day of his wrath." Psalm 121:5, "the Lord is thy Keeper; the Lord is thy shade upon thy right hand." The idea is, that as we use the right hand in our "own" defense, we seem to have an additional and a needed helper when one is at our right hand. The sense here is, that the psalmist felt that God, as his Protector, was always near him; always ready to interpose for his defense. We have a somewhat similar expression when we say of anyone that he is "at hand;" that is, he is near us.

I shall not be moved - I shall be safe; I shall not be disturbed by fear; I shall be protected from my enemies. See Psalm 10:6; Psalm 15:5. Compare Psalm 46:5. The language here is that of one who has confidence in God in time of great calamities, and who feels that he is safe under the divine favor and protection.

Psalm 16:8 Parallel Commentaries

Source of My Life's Refreshing Springs,
"Thou maintainest my lot." -- Psalm 16:5. Source of my life's refreshing springs, Whose presence in my heart sustains me, Thy love appoints me pleasant things, Thy mercy orders all that pains me. If loving hearts were never lonely, If all they wish might always be, Accepting what they look for only, They might be glad, but not in Thee. Well may Thy own beloved, who see In all their lot their Father's pleasure, Bear loss of all they love, save Thee, Their living, everlasting treasure. Well may …
Miss A. L. Waring—Hymns and Meditations

Period iv. The Age of the Consolidation of the Church: 200 to 324 A. D.
In the fourth period of the Church under the heathen Empire, or the period of the consolidation of the Church, the number of Christians increased so rapidly that the relation of the Roman State to the Church became a matter of the gravest importance (ch. 1). During a period of comparative peace and prosperity the Church developed its doctrinal system and its constitution (ch. 2). Although the school of Asia Minor became isolated and temporarily ceased to affect the bulk of the Church elsewhere, the …
Joseph Cullen Ayer Jr., Ph.D.—A Source Book for Ancient Church History

The Wrath of God
What does every sin deserve? God's wrath and curse, both in this life, and in that which is to come. Depart from me, ye cursed, into everlasting fire.' Matt 25: 41. Man having sinned, is like a favourite turned out of the king's favour, and deserves the wrath and curse of God. He deserves God's curse. Gal 3: 10. As when Christ cursed the fig-tree, it withered; so, when God curses any, he withers in his soul. Matt 21: 19. God's curse blasts wherever it comes. He deserves also God's wrath, which is …
Thomas Watson—The Ten Commandments