We don’t use the word "joy" a lot these days. The Google Ngram below shows that the words "joy" and "happiness" occur with about the same frequency, but if you add "happy" and "happiness" together, then they occur about 3 times as often as "joy". They can mean the same thing, but I think of happiness as a passing emotion that depends on external circumstances, whereas joy reflects a deeper sense of contentment, wonder and satisfaction that doesn’t depend on circumstances.
An author who influenced me a lot in younger days was C.S. Lewis, whose auto-biography was called "Surprised by Joy". Late in life he married a woman called Joy Davidman, but that happened after he published the auto-biography, so the book wasn't about being surprised by her. In fact the book is about the intense longing we feel for something supremely good, for a state of all-right-ness that the Hebrews called Shalom. Joy is a longing for the source of that goodness, a longing that can hardly be put into words. It is never found by looking for it, but found by surprise when seeking something else. Joy is like finding out that the thing you most wished were true actually is true.
I heard Prof. Miroslav Volf speak in Sydney last year, a theologian whose core topic for many years has been identifying the good life. People often say they want a good life, but what do they really mean?
He said it is very sad that religion often seems to imply that doing what is good and doing what is fun are mutually exclusive -- that if you do one you can't be doing the other. (It reminded me of what it seems like with food. The really yummy food is often not good for you and the food that's good for you can taste awful.) But Volf says that is a stupid idea. He said that we all wish for both pleasure and meaning and the good life has them both. We want to enjoy what we do. We want to do things that contribute to some greater purpose.
The best line of the lecture … I think I will remember it for a long time … was that joy is the unity of meaning and pleasure.
May we all find that true and deep joy. Don't settle for the fool's gold
of surface-level happiness but seek all that is true, noble, right,
pure, lovely and admirable; and in doing so may you often stumble into