I don’t know if you knew it, but Jesus actually was a pretty happy camper. As a matter of fact he was happier than “any on his companions” (Hebr 1:9). Scripture also says that “in His presence is the fullness of joy” and “pleasures forevermore” (Psalm 16:11).
I think it’s safe to say that there’s plenty of reason for believers to be the happiest people on earth. If you’re still not convinced of the benefits of joy, have a look at these scientifically proven facts about what laughter can do for you: