This has nothing to do with how joyful you are as a person, but brownie points to you if you automatically replied “yes!” before you even read beyond the post title!
“Planetary joy” is something of an older, traditional thing that’s not used as often anymore. It designates each of the seven traditional visible celestial bodies a house that they are/were purported to really express their inherent qualities the best in. A planet in a house it “rejoices” in gives that planet a type of dignity. A lot of people know what essential dignity is: a planet in its domicile, for instance. (Mercury in Gemini -the sign it rules- would have essential dignity.) Planets can also have dignity if they are in a house of their jollies. These things did not come about by guesswork or accidents; there was good reason underlying the matchmaking or it wouldn’t have stuck around for long.
So, what houses do the traditional planets find “joy” in?