To go greet Moshiach one must go with simcha

My father-in-law the Rebbe said that we are on our way to greet Moshiach Tzidkeinu, and when going to greet Moshiach Tzidkeinu one must go b'simcha.

However, when a person makes an honest accounting of himself, where he is holding and what his spiritual state is--he could think: what does he possibly have to be happy about?

Regarding his situation itself -- "yada inish b'nafshe", a person knows his spiritual standing; even regarding the Torah and Mitzvos that he does fulfill -- he is unable to feel what is brought about by his fulfillment of Torah and Mitzvos, since at the present time all these matters are in a way of "matan b'seiser" (gifts given secretly), as though kept in a sealed chest. If so, how can he be b'simcha?

The answer to this is: he must know that all that is drawn down via Torah and Mitzvos is being drawn down now, in the time of golus, and in the time to come all the things drawn down through Torah and Mitzvos now will be revealed. And when he makes an account, that the truth of the matter is that all of these things already exist now, and ultimately they will be revealed--this brings to simcha.

Lubavitcher Rebbe, Parshas Kedoshim, 5714