“Rejoice in the Lord always; again I will say, rejoice.”
— The apostle Paul, from his letter to the Philippians (4:4)

To rejoice is to have a constant and controlling awareness of the steadfastness of God’s love for you, to continually remember at all times and in all circumstances the constancy of Christ, and to live out life in that assurance. That is what Paul is commanding. It is not the importing of some emotion that is foreign to the moment. Rather it is simply a willing and determined faith in the promises of God no matter what feelings are rolling over you. This is how we can be afflicted in every way, and yet not crushed. This is how we can grieve through genuine pain, and yet still remain confident in the redeeming and gracious presence of God.

This is how we rejoice always.