1-2 My heart is steadfast, O God! I will sing and make melody with all my being! Awake, O harp and lyre! I will awake the dawn! I will give thanks to you, O Lord, among the peoples; I will sing praises to you among the nations. For your steadfast love is great  above the heavens; your faithfulness reaches to the clouds. 5-6 Be exalted, O God, above the heavens! Let your glory be over all the earth! That your beloved ones may be delivered, give salvation by your right hand and answer me!

7-9 God has promised in his holiness: “With exultation I will divide up Shechem and portion out the Valley of Succoth. Gilead is mine; Manasseh is mine; Ephraim is my helmet, Judah my sceptre. Moab is my washbasin; upon Edom I cast my shoe; over Philistia I shout in triumph.”

10-11 Who will bring me to the fortified city? Who will lead me to Edom? Have you not rejected us, O God? You do not go out, O God, with our armies. 12-13 Oh grant us help against the foe, for vain is the salvation of man! With God we shall do valiantly; it is he who will tread down our foes. Psalm 108 (English Standard Version)

Who of us has never faced setbacks in life? Whether it was in the career we were pursuing, our health, our finances, our marriage and family, perhaps even a work we sought to do for the Lord, there were probably some discouraging setbacks along the way. At such times Christians may have felt the Lord had somehow forgotten, even forsaken, them. What was the setback vs 10-11 suggest David was experiencing?

His army had met up with strong resistance which they were not able to overcome. It may may've been the seemingly impenetrable mountain fortress of Edom mentioned in vs 10-11. The Psalm is set in the years we read of in 2 Samuel 8 when David was extending his kingdom and had been experiencing many victories. But suddenly things were going wrong. So how did David respond to this serious setback? What was his response we see in vs1-4?

I'd suggest it was praise. It's a lovely phrase where he says he would 'awake the dawn' with praises to God. He especially praises God for His steadfast love and faithfulness. Some of us may respond to setbacks by not wanting to get out of bed to face the day's problems. David started the day with praise. And what was his response in vs 5-6?

He prayed. He prayed for God's name to be hallowed and for God's will to be done. He prayed that God would come to the aid of His beloved child and people. Setbacks ought not to drive us to despair, but to heartfelt prayer. What was the next thing he did in vs 7-9?

He looked to God's promises (and perhaps also recalled past deliverance). Psalm 108 is a combination of Psalms 57 & 60. And in Psalm 57 David's setback had been that King Saul was pursuing and seeking to kill him. But God had saved him then and given David assurances of His plans for him. So David drew strength from God's promises. Hebrews 11:6 reminds Christians of a promise where God says “I will never leave you nor forsake you.”

There was one more important thing David also did which we see in vs 12-13 (and which he expressed in the opening words of the Psalm). What was that?

I'd say it was that he persevered. He remained steadfast. He asked for God's help because he still believed that with God we can do valiant things. He knew that setbacks (even those that were beyond the help of man) need not be final. William Carey was a pioneer missionary in India. One day a devastating fire burned down the printing press he had built, destroying Bible's and many years of painstaking manuscript translations. Carey was heartbroken, but he patiently started to redo the work that had been lost. He too persevered in the conviction that with God we can do valiant things. I don't know for sure if Edom was the insurmountable setback David faced, but 2 Samuel 8 tells us that David went on to defeat the Edomites and they were subjected to him. What looked impossible for men was possible for God.

There's a musical version of this Psalm which is quaint, but faithful to the words. It's at https://www.youtube.com/watch?v=qxz_lapY_0Q&ab_channel=JanetIsaacMorrison