Please review my resignation letter

This is my first time quitting a job. I'm a work-study student at a college, and work as a clerical associate at the college. I've only been there for 4 weeks, and I was crying on my way to work because I hated it so much. I am the director's only assistant, so I feel bad doing this.

Good morning Mr. *****,

I thank you for hiring me and for your guidance. After much thought, I have chosen to resign from this position. This was not an easy decision for me to make.

I have come to the realization that I am unable to balance my work schedule and school.

I am sorry for the inconvience this may cause and wish you great success.

Best,

*****