people in the world believe that joy is "the emotion of great delight or happiness." [source.] they just don't get it. joy isn't an emotion, it is comfort in knowing that God will always be there when we need Him. [that is where happy comes in.] God doesn't give you joy just to make you happy, He gives it to you to go and let others see the source of your happiness. [which in the end, will make you happier than you can imagine.] :)
Phil 1:26b "...your joy in Christ Jesus should overflow."