But you, O LORD, are a shield about me, my glory, and the lifter of my head.  I cried aloud to the LORD, and he answered me from his holy hill. Selah (ESV)
We know the context of this Psalm because the title of the Psalm reminds us that this was written when David was on the run from his son, Absalom. Absalom was trying to take the throne away from his father. It was bad enough for David that his son is trying to kill him and take his kingdom. Additionally, he had to deal with being cursed by some of his own people. How does David respond?
David looks to the Lord as his shield, and the one who lifts up his head. He had the confidence of knowing that when he called to the Lord, he would be heard. The image of a shield is not one we use in modern language. But, in David's day, a shield was a vital means of defense from the enemy. God was the shield that David relied upon for safety.
David could have easily given up on life. After all, his son wants to kill him. Those who used to support him have turned on him. But, he does not let himself stay down. He allows the Lord to lift up his head. So often, when we are faced with even the smallest adversity, we give up. We fall for the lie that God does not care for us, and become overwhelmed.
David teaches us the value of allowing the Lord to lift us up. The great Apostle Paul knew what it was like to go through great adversity. He had been shipwrecked, beaten, robbed, unjustly imprisoned, without food, and even clothing. Listen to his words given to us in Romans 8:31:
 What then shall we say to these things? If God is for us, who can be against us? (ESV)
Are you feeling down? Have you been unjustly attacked? Maybe you have even been betrayed by those who once were your greatest support. Look to the Lord. He is for you, not against you!