Opening the book…
Cool detachment is cheap and it costs the room something. Enthusiasm is contagious in a way irony never is, and people remember how energised they felt around you far longer than they remember anything clever you said. Hiding what you love to avoid looking naive means nobody ever gets to be delighted alongside you.
Say the thing out loud: that you have read this book four times, that the bird outside the window is worth stopping for, that you are genuinely excited about a spreadsheet you built. Let your face do what it wants. When someone else shows you their obsession, ask a second question instead of a polite nod.
Read the room when someone is grieving or under pressure — your delight can wait an hour. And enthusiasm that requires an audience to perform for is vanity, not joy.