The majority of my personal leave days are for mental health in my mind. Those days you wake up and say "nah fuck this shit, not today", or where I've had a shit sleep and could work but would be hating every second and not doing a great job. Or because work has actually been really rough and I'm stressed out and need a breather. I have no guilt taking these days off. I also do not straight up say they are for mental health, none of my companies business. It's a sick day and if they want me to get a med cert I will (but thankfully they rarely do).