Joy is not the absence of difficulty, hardship, or struggle; joy focuses on the purpose of God in “the dark night of the soul” because weeping doesn’t have the final say, God does.
Joy grasps the truth that God is at work even in most trying circumstances, whether one is aware or unaware of it: God does His best work in the worst places and shows His amazing grace in the worst time.
The joy of the Lord is our strength when we understand that our trying circumstances are the training grounds where God’s unfolding story of redemption is magnified. Even if all is against us, God is for us; for nothing can separate us from the love of God.
Just because there’s weeping at night it doesn’t mean that God is absent. He is doing deep work in and through tough circumstances; the darkest point of the night is the beginning of dawn.