The LORD gave David victory everywhere he went
The key verse of chapter 18 is verse 6, it is repeated again in verse 13.
God is a faithful God, in this chapter, he is fulfilling His promise to David in chapter 17:8 [I have been with you wherever you have gone, and I have cut off all your enemies from before you. Now I will make your name like the names of the greatest men of the earth].
David recognized the victories he had were from the Lord. His heart continue to seek the Lord, this can be seen by David’s action to use collect bronze, silver and gold for the building of God’s temple (v8,11).
We, like David, are in battles as well. Our battles are not physical, but spiritual. Our enemies are Satan, the World, and our old self. The only way to win these battles is to follow our Lord Jesus, because the Lord Jesus had already won the war on the cross. When we deny ourselves and carry our cross to follow our Lord, His victory became ours.