That was always an issue I ran into. In a given month I might have two of three days that my brain just didn’t work. I’d stills go into the office and be absolutely unproductive. But to my boss, being in the office was the important thing. As I only got ten days of PTO a year including medical leave and business holidays I was never going to waste it on a mental health day. Was far better to sit at my desk and pretend like I was productive.