Surprisingly, I love working, and deal with frontline positions really reall well. Work actually gives me confidence, and makes me feel a lot better even outside work.
My first job I got through my mom, and it was as a weekend receptionist. Except no one told me I'd have to work weekdays, talk over the PA very often, and herd the crowds when we had about a hundred or two people for an event. Being forced to do that probably 'fixed' a bit of my SA; I actually made friends there that I still keep in touch with.
The second job was as an assistant to IT, and I got to literally crawl around 15 huge offices. I went on and under desks, looking like an idiot with everyone wondering, then asking what I was doing. After a while, you just stop caring about looking/sounding stupid. That and the powertrip of being an employee, telling people what to do in your building/office helps to build confidence.
My worst job was the one where I did data entry, and didn't have to talk to anyone, but my supervisor. I was a temp, so no one really bothered either. It was more awkward cause when I got the chance to talk to people, it was hard to initiate cause we'd been ignoring one another for over a month.