Psalm 89:17 For thou art the glory of their strength: and in thy favour our horn shall be exalted.

The glory of our strength is the word of God (Jesus). i.e. Our strength to think or do right comes from it/him and therefore he receives all the glory for it.

Philippians 2:13 for it is God who is at work in you, both to desire and to work for His good pleasure.

The exalted horn (king/power) is also Jesus. God's favour allowed him to be lifted up for our sakes. He was crowned (thorns) and lifted on the cross (exalted as king) to save you and I.

John 12:32-33 And I, if I be lifted up from the earth, will draw all men unto me. [33] This he said, signifying what death he should die.

He is the horn of our salvation. We can't live (which includes thinking and doing his will) without him. Selah!