Lamentations 3:18 - Ellicott's Commentary On The Whole Bible

I said, My strength. — The sorrow of the mourner comes to the very verge of despair. There was “no help for him from his God;” even that hope had left him. But, as the sequel shows, this despair was the beginning of a reaction. The very name of Jehovah (no longer Adonai) reminded him of the everlasting mercies.