Here are a few textual excerpts that express upbeat, optimistic, and/or joyful feelings...
Diogenes Laertius, book 10, excerpt:
"Also that in his letters he wrote to Leontion, "O Lord Apollo, my dear little Leontion, with what tumultuous applause we were inspired as we read your letter." Then again to Themista, the wife of Leonteus : "I am quite ready, if you do not come to see me, to spin thrice on my own axis and be propelled to any place that you, including Themista, agree upon" ; and to the beautiful Pythocles he writes : "I will sit down and await thy divine advent, my heart's desire."....It is observed too that in his treatise On the Ethical End he writes in these terms : "I know not how to conceive the good, apart from the pleasures of taste, sexual pleasures, the pleasures of sound and the pleasures of beautiful form."
De Rerum Natura, book 2, excerpt:
Will add soon [sunshine, birds-song in forests]
...More to be added soon
Feel free to post any other upbeat, optimistic, and joyful Epicurean text excerpts.