The dire consequences that will befall you will be “Because you did not serve Hashem with joy” (Deuteronomy 28:47)
If we are not feeling joy in performance of the mitzvos, we must not be doing them right. The knowledge that we are doing what God wants us to do, thereby fulfilling the purpose of our existence is reason for euphoria.
We can convert everything to a mitzvah. We must have energy and strength to do mitzvos, and if eating and sleeping provide us optimum health so that we can do the mitzvos, these actions, too, are accessories to mitzvos. If we dedicate our lives to the will of Hashem, we can experience joy in everything we do.