Sometimes, it makes sense to simply state that you have burned out on your job. This letter is a chance to not only resign, but to highlight workplace mental health and lifestyle issues that could useful for a soon-former employer to know.
Please accept my resignation, effective in two weeks’ time.
I am simply suffering from burnout. After the year that we have had, I’m sure you can relate.
As much as I’ve enjoyed my work at XYZ Company, I’ve finally realized that no job is more important than my physical and mental health.
I appreciate your support, as well as your guidance over the years. I will miss the entire team.