“Serve Hashem with awe, and rejoice while trembling” (Psalms 2:11)
This appears to be a bit inconsistent. Joy does usually not accompany awe and tremors.
A chassid once came to the Alter Rebbe ( Rebbe Shneur Zalman of Liadi, author of Tanya), and presented him with a kvittel (petition), in which he enumerated his many needs. The AlterRebbe studied the kvittel and said, “It seems that you have given much thought to your needs. Have you also given much thought to why you are needed?”
The chassid was shaken up with this reprimand. He had been concentrating on his needs, but had not given too much thought to whether he was accomplishing the purpose for which he was created.
Yet, this sharp reprimand was uplifting. There is no depression worse than feeling worthless, that one serves no purpose. Being reminded that he was needed, that there was a special mission for which Hashem created him, was exhilarating.
The sefarim tell us that Hashem waits for our prayers and takes great pleasure in our mitzvos. The Psalmist says, “Fortunate is the person who fears Hashem, who has great desire for His mitzvos” (Psalms 112: ). One of the Chassidic masters said that the verse can also be read as “Fortunate is the person who fears Hashem,. He ( Hashem) has great desire for his mitzvos.” I.e., Hashem has great desire for the mitzvos of those who fear Him.
Thus, there can be joy amidst tremors. Tremors of awe, and joy in knowing how important one is to Hashem, and that one’s life has meaning.