Mania at work

This mania is a problem at work. I am very self conscious of blurting things out too loudly and cheerfully. For instance I said it was a good headset that I put on because the customers ordering food didn't sound like "mwaah mwah mwah mwah" (covering mouth with my hand). I don't have the soothing calmness and "strong silent type" mood that I usually want to project, but instead a frightening, obnoxious, irritable mood. There is one particular girl who is anxious and who I want to be calm around, so that she will trust me. I feel too overbearing.