Why is it a Mitzvah to Be Happy on Yom Tov?

In the frenzy of shopping, cooking, cleaning, it can be easy to
forget the important parts of Yom Tov. Like being happy! Rabbi Moshe
Elefant explains the mitzvah of Simcha of Yom Tov.

Learn more about the laws of Sukkot and Yom Tov.
http://www.kosher.com/shows/ou-you-25