From The Maagid:

Our sages teach “God wished to bring merit / purify the Jewish people, therefore He gave them many Mitzvos” – explains the Maagid this actually refers to infinite – because a Jew every moment has the Mitzvah to “serve God in all your doings” – as such, you can light your life.

Now when a Jew does Mitzvah with passionate love/reverence for God this causes upon him to dwell the Rauch Hakodesh (the holy spirit.)