What is divine wisdom?
Divine wisdom is the inner delight of the Infinite, condensed and crystallized until fit for human consumption.
What is a mitzvah?
A mitzvah is divine wisdom condensed and crystallized until it can be performed as a physical action.
That is why in the study of Torah there is infinite delight.
That is why in the act of a mitzvah there is unlimited joy.
Maamar Arbaah Rashei Shanim Heim, 5731. Tanya, Igeret Hakodesh 29.