This verse is part of a hymn, a song. It seems like it doesn’t even belong in the New Testament because it certainly has a New Testament feel. Lots and lots of evidence of what was to come in Old Testament scripture.
Come what may because God is my strength and I will not be afraid! I cannot stand strong without the strength I’m given in my relationship with God! God is my salvation and I’ll trust in Him.
As a young person I grew up singing the last part of this verse. I can hear our group singing it even now in my memories. We added, “And I will prepare him my heart”. I have work to do here to prepare my heart. Without this preparation the Lord won’t be my strength and my song. My flesh will take over and win if I don’t declare today the Lord is my foundation, my song, my strength, my shield, my superpower! Things here may appear awful but I know God is my salvation and worthy of my trust. God gives us all we need to endure anything this life presents. I have to trust and obey. All my eggs are in this basket. My heart is at peace. I know this more deeply than I know anything else!