Is it possible to have a Generalized Anxiety Disorder and Depression, and still be a functioning employee?

I have been in some state of anxiety or depression for the past month. Some days/weeks are better, some worse. Part of my anxiety is a fear for my future. I know people with depression and anxiety who have a hard time keeping a long-term, stable job, and thus not being able to support or take care of themselves because of financial issues. I have this fear that "it's not possible to suffer from mental illness and be a successful employee."

Currently, I am an intern and love my job and am doing well at it, but it's temporary. I am also going back to school for a career change as my field (natural resource management) is no longer a good fit given my health issues.