Everything must begin with awe; everything must lead to joy. One who feels awe and stops there lives in torment. One who feels joy without awe loses that joy within the snare of ego.

It may seem ironic, even paradoxical, but it is in the realization of our own nothingness, trembling before the awesome presence of the Infinite, that true joy is born. For, as small as we are, we are related to that awesome presence. We are its children, and its privileged servants.

לעבוד את השם ביראה ובשמחה, והן תרין ריעין דלא מתפרשין, ויראה בלא שמחה היא מרה שחורה, ולא יאות לצער על עבודת ה׳ האיך לעבוד, רק תמיד יהיה בשמחה, ואפילו באותה שעה צריך ג״כ לעבוד אותו, ואין פנאי לישב אותו איך ומה

They are two companions that must never part.

Serve G‑d with reverence, with a sense of awe and nothingness before the Infinite, and with happiness. They are two companions, complementing one another, that must never part.

Unhappy reverence is a gloomy attitude. It's not nice to torment yourself over the way you serve your G‑d.

Rather, always be happy. No matter what sort of a time, you still must be serving Him. Don’t waste your time fretting over how and what.

—Tzava’at Harivash 110