"For seven days you shall eat matzah..." (Shemos 12:15)
On the first night of Pesach, every person has a mitzvah to eat matzah.
This serves to remind us of the wondrous events that occurred when we left
Egypt and of the great principles which we learn from the Exodus.
By law of the Sages, one may not eat matzah the day before Pesach, so that
one will have more of an appetite for it on the seder night.
Matzah must be baked within eighteen minutes so that it will not become
chametz. This is a model for all mitzvos, since our Sages teach
that every mitzvah should be performed with alacrity so that it does not
become "chametz" (Mechilta, Shemos 12). We must strive to
serve Hashem with zerizus, energy and enthusiasm.