New Job

Does anyone know why starting a new job is always hard? I work with great people, at a great place, getting up at basically the same time as when I was in school, but I'm feeling pretty overwhelmed by the new job. Working in a hospital is pretty much like you'd expect it to be. I sit in meetings almost all morning, listening to people talk about things they are working on in their committee. I'm surprised people can even keep all the acronyms straight!