One thing that surprised me about the change from grad student to professor is how shy I felt about doing "faculty" things. Checking my department mailbox. Using the copier. Going to meetings.
When I was in high school, I once knocked on the door of the faculty break room during lunch hour, in search of a teacher. Nobody shooed me away, but there was still the feeling that students were verboten from the break room. (And why not? Some of those teachers seriously needed a break from students, if only for a few minutes.)
The first time I went into the Briggs break room I had the same feeling. Like I'd trespassed in Grown-up Land. Except I'm a grown-up too. And I'm a professor too. And I'm totally allowed—even expected—to be there.
I consider how I would feel if there were no other women, or if I were some other minority in the department, or if my college and colleagues were not so supportive. This is how many people do feel, and it's not just in their heads—many workplaces are not welcoming and inviting, people are made to feel uncomfortable and othered. I am lucky that most of what I face is internal. Nobody's actively pushing me out. In fact, they keep welcoming me and encouraging me. They want me to succeed.
I realized I was asking everyone around me for permission to be there, and that was undermining my confidence. I don't need anyone's permission to do my job. I'm the real deal, not an impostor.
Like the spy movie cliché, people tend to assume you belong and you know where you're going. You just have to act like it. Do it long enough, and you might just fool yourself.
So when I feel uncertain now, I just act. I pretend confidence, and the confidence becomes real.