I have never been fired but have had to resign due to being unable to continue working with my mental illness issues. The job i have had the last three years I have always taken time off sick when really unwell so my behaviour isn't noticed by colleagues etc. As I am casual I can take time off whenever, to a point. I am a great worker when well so I think that is why they have put up with my many absences. My boss now knows I have mental illness issues (but not which ones) and is supportive. By the time I go back to work in January I will have had 2 months off. Thankfully there is a shortage of staff in the area I work in so I am not replaceable at present.