In yesterday's Zoom a topic came up (very briefly and not in any detail) that could be very rich and also in need of exploration...prayer.
I don't think we have any direct evidence of prayer by Epicurus, and since he was a materialist perhaps he did not do any prayer. I would define our current understanding of prayer as distinct from ancestor rituals or sacrifices to ancient gods. Here in the US, the way that prayer is currently thought of is often originating from Judeo-Christian ideas and prayer rituals. Then there is the New Age movement which expanded that to include Hinduism and Native American (etc.), but they are all based on the idea that one's thoughts can affect the Universe and that God or the Universe is listening and will grant your wishes if you pray with a pure heart. For those people who are raised in a religion but then moved on and over to studying Epicurean philosophy, then it may seem that the habit of praying is still there in the mind or the back of the mind. And for those who feel clear about the nature of the Universe this could then create a cognitive dissonance.
A main benefit of prayer is the development of a feeling of courage. (And a related question is does Epicurus or Philodemus say anything about courage).
There is the famous AA prayer: "God grant me the serenity to accept the things I cannot change,
Courage to change the things I can, and Wisdom to know the difference." And this can be compared to this excerpt in Letter to Menoeceus: "He understands that the limit of good things is easy to fulfill and easy to attain, whereas the course of ills is either short in time or slight in pain; he laughs at (destiny), whom some have introduced as the mistress of all things. (He thinks that with us lies the chief power in determining events, some of which happen by necessity) and some by chance, and some are within our control; for while necessity cannot be called to account, he sees that chance is inconstant, but that which is in our control is subject to no master, and to it are naturally attached praise and blame."
I think that a downside of prayer is that it could get in the way of knowing specifically what you want, because sometimes a prayer originates from a vague "feeling" and not a specific "want" - for example saying to yourself: "I pray that everything will turn out okay" vs "I would like to have a safe journey and feel relaxed, and now I can think of specific ways that I could go about increasing my safety and relaxation". So getting in touch with desires and specifically spelling out those desires can be more empowering then prayer when you think about specific actions you can do...and thus leading to greater courage.