That's right, you have a godly right to do so. Rejoice means happiness, joy, gladness, delight, elation, jubilation, exuberance, exultation, and celebration. How awesome is that! I love it. We have much to rejoice for, because the Lord has us here for a reason. We should rejoice and be glad in that.
I know how it is not to rejoice, but after I got out of my dark place of regret I came to realize that we all can rejoice even when negative situations and challenges confront us. Yes, there will down times, because we're human. Yet, having joy and rejoicing means we don't have to remain in that state. We can draw our strength from God even when chaos can be going on around us. Yes, we can have a calm and "rejoicing" spirit. "And there you shall eat before the Lord your God, and you shall rejoice, you and your households, in all that you undertake, in which the Lord your God has blessed you" (Deuteronomy 12:7). Rejoice.