Psalm 16:2 (ESV) … “I say to the Lord, “You are my Lord; I have no good apart from you.”
The concept of God as his refuge was fundamental to the psalmist, the foundational principle of his life, the immovable rock upon which he would stand. It involved a disavowal of allegiance to any other deity. I said to the Lord, “You are my Lord; apart from you I have no good thing.” This unreserved commitment to the Lord is the secret of his happiness and it entertains no desire to turn to any other.
Moreover, draw encouragement from this entire Psalm. For this Psalm 16, has been called an Easter Psalm. When we read the Gospels, Jesus’ courage as he faced death—his sheer guts—are absolutely amazing. He was a real human, like we are—how could he have been so brave as he was about to be killed? What was going on in his heart? What was he praying when no one else was around? How could he be sure he would rise again? Jesus was fully human; he had thoughts and emotions just like you and me. Psalm 16 gives us a window into his soul. This is how the real man, Jesus, strengthened his soul as he faced the cross.
The Holy Spirit inspired this Easter Psalm so we could strengthen our souls in Christ. We may be facing some trouble or hardship that shakes us to the core. Jesus’ thoughts need to be our thoughts. His feelings need to become our feelings.
As David speaks for Christ, this psalm expresses his commitment (vv. 1–3), his contentment (vv. 4–8), and his confidence (vv. 9–11). It seems to me that these are in order. Commitment to God brings contentment in God that leads to confidence in God.
 Tesh, S. E., & Zorn, W. D. (1999). Psalms (p. 170). Joplin, MO: College Press.  Johnston, J. A. (2015). Preaching the Word: The Psalms: Rejoice, the Lord Is King—Psalms 1 to 41. (R. K. Hughes, Ed.) (Vol. 1, pp. 174–175). Wheaton, IL: Crossway.