I think it would be good to check the meaning of the word so that we can all come to this with the same angle.
First of all, I am glad.
Second of all, the promise is there for anyone who wants to be glad. You see, God answers and hears our prayers releasing us from our fears and terrors. Our gladness is not just normal gladness, it is radiant, beaming, and lightened. People will notice that you are glad. Your face will not longer be that of someone confused and ashamed.
Those who are poor, those who are suffering, those who are going through troubles and distress – there is One who can make you happy. He can be your refuge, a place of blessing and trust for those who follow Him. You will become His sons and daughters. You will not lack because you will become children of God.