I'm gonna keep it brief. I went to this place for a job a few days ago, as soon as I stepped in I felt uncomfortable. I talked to the manager, he was willing to hire me on the spot and I was too anxious to not accept (I know, I'm dumb). I start next week, I'm absolutely terrified about going in, I didn't like the look of the place or the workers at all. Is it fair to tell them I changed my mind? What's the best way of doing this?