the strength of my salvation,

David praises God wholeheartedly. Praise is not just a song about God; it is a song to God. Praising God has several aspects to it: 
(1) Say thank you to him for each attribute of his divine nature; 
(2) focus our hearts on him; 
(3) thank him for his many gracious gifts to us; and 
(4) thank him for our relationship with him.

2 Samuel 22 (New Living Translation)

1 David sang this song to the LORD after the LORD had rescued him from all his enemies and from Saul. 2 These are the words he sang: "The LORD is my rock, my fortress, and my savior; 3 My God is my rock, in whom I find protection. He is my shield, the strength of my salvation, and my stronghold, my high tower, my savior, the one who saves me from violence. 4 I will call on the LORD, who is worthy of praise, for he saves me from my enemies. Read 2 Samuel 22