Everyone has good days and bad days! If you can learn even one thing about yourself or what you're doing on a day that you struggle, then apply it to the next time you're in the same situation. You will always be doing better than before!

I work in fast food as well. When I started I was terrible. I messed up taking a lot of orders and I didn't really know what to do with my time so I hid in the lobby as often as I could get away with, wiping down tables and cleaning trays. It wasn't until I stuck with it and started asking questions about how to do it or why we do things a certain way that I was able to apply what they were showing me and get better.

Point of the story is! It's okay to be new at things, it's okay to suck at things, but you can get better! Don't be afraid!