I found that this is also a sign of mental overload, probably PTSD. I KNOW I will have to interact with people, p.e. write a fucking letter, but my people interaction batteries are totally drained from work/kid/wife/whatever. For me it is a sign that my brain/self just can not do this task. Probably think about what general category your task falls in and think about that respective battery level. Might not help to do the task, but to get to know the reason to why not.