Besides living in the Sukka and taking the four species, in Sukkot we have another Mitsva called “simha”, happiness.
Yes, we are commanded to be and behave in a happy way, every Yom Tob and particularly in Sukkot.
Although, we are used to the idea that happiness is a result of success, and that success consists in having more, gaining more, etc. the Jewish vision of happiness is a little different. If success is getting what you want, happiness is wanting what you got. In Yom Tob we learn to be happy with what we have, regardless of what we have or how much we have.
We are also happy to belong to Am Israel, by knowing that HaShem protected us in the desert and that we are still under His permanent care.
Part of this Mitsva consists in the enjoyment of material happiness. In Yom Tob we share many festive meals with our family, (wine and meat are a must in any Yom Tob’s menu). We eat and drink, we honor the day and we make it pleasurable, as we do with Shabbat (Shulhan ‘arukh OH 529:1).
In honor of Yom Tob, we also need to dress well, or according to the Shulhan ‘arukh, we should dress better than Shabbat. (idem.)
The hakhamim also specified that each individual enjoys material happiness in a different way. They said that before yom Tob begins the parents should get for their children “…roasted nuts and walnuts (=the equivalent today of candies and small toys); the husband has to buy clothing and jewelry to his wife, at the level he can afford.
We are also obligated to share our happiness with those who don’t have enough. We should provide food for the stranger, the orphans, the widows and other poor people” (SH. ‘A 529:2).
Maimonides elaborated on this last point: ” One who locks the doors of his courtyard [to the needy] and eats and drinks together with his children and wife, and does not feed and give drink to the poor and needy, is not feeling the joy of a mitsva, but the joy of his own stomach . . .” (MT Yom Tob 6:18)
This simha also requires moderation (even if you are not going to drive). “During yom Tob [this includes Simhat Tora. Y.B.] a person should not drink too much… because drunkenness and frivolity is NOT part of the Mitsva of happiness, but foolishness and licentiousness… and we were commanded to attain a level of happiness that is part of worshipping HaShem… and one cannot worship HaShem by frivolity and drunkenness” (Idem., 6:19)
“The greatest way to worshiping God is by being happy because we are doing the commandments of God, and being happy because we love our God” (MT H. Sukka veLulab, 8:15).