The application considers the theme of joy through contents present in the Bible, in the diary of St. Faustina, in the text of songs and poems.Pope Francis gave the universal church the apostolic exhortation "Gaudete et exsultate", which is an invitation to joy and exultation addressed to all Christians. An evangelical urgency resonates in it to which Pope Francis is very attentive, because he considers it decisive in the life of Jesus disciples: the urgency of joy, which is the joy of the Gospel, the joy of love, the joyful experience of communion with the Lord Jesus.We know the reproaches addressed to us Christians in particular by Friedrich Nietzsche at the beginning of the last century, on our faces which often appear sad, tired, depressed, asthenic and even cynical. We are crushed by the weight of the precepts, in profound contradiction with the message of the Gospel which is "good news", an announcement that should arouse joy and exultation: the joy that arises from an encounter that gives meaning to existence; the joy of discovering an incalculable treasure; the joy of liberation, of the fullness of life that the Lord offers to those who welcome his love, which must never be deserved. Unfortunately, Christians forget that joy is an apostolic command, addressed by Paul to the church: "Rejoice always in the Lord, I repeat to you: rejoice!" (Philippians 4, 4).