Be wary of “mental health days”.
Every once in a blue moon, you may well and truly need one. I have found; however, that what I really need is an order to my days and the ability to “turn off” work on regularly scheduled days (maybe it is Saturday or Sunday), but right now, it is rarely both.
Having one day a week that you can count on as “I don’t have to think about work day” really does help you recharge.
Otherwise, you find yourself escaping into “mental health days” far too often on days you should actually be working.