In the letter’s four short chapters the author continually exhorts us to praise God no matter how dark our circumstances are. He writes: "I will rejoice" (1: 18, NASB), "I rejoice and share my joy with you all" (2: 17), "I urge you, rejoice in the same way" (2: 18), "Finally, my brethren, rejoice in the Lord" (3: 1) and "Rejoice in the Lord always; again I will say, rejoice!" (4: 4).
When any type of electronic equipment goes out of whack, a reset button will get it back online. That is what happens when we rejoice: The joy we’ve lost is restored and our feeble faith rises again.