G-d wants us to put the message of our festivals on our hearts. Once this happens we become closer to G-d.
The longest distance known to man is the distance between the head and the heart.
Moses then reviewed with the Jewish people the laws of the three “pilgrim” festivals – Passover, Shavu’ot, and Sukot – which they were required to celebrate in the Temple-city.
[Moses told the Jewish people,] “You must rejoice in your festival.” Deuteronomy 16:14
Rabbi Shneur Zalman of Liadi, the founder of Chabad Chasidism, interpreted this phrase as follows.
“You should internalize the inner message of the festivals. This will infuse joy into your observance of the festivals; they will become your own, personal celebrations.”1 Sefer HaSichot 5704, p. 82.