It is so hard, isn't it?!

I took a job that for years I said I never wanted. When I took the job, I decided that my not taking a similar job before was in part because I was avoiding responsibility, or opportunity. I can't figure out if I am now resisting growing into the job, or if it was a big mistake. I feel so anxious about it alllll the time, I have so much stress from it.
Many days, I just want to 'give it back'.
What to do is a very good question.

I hope you find your answers and peace.