Thank you Jean! As a person who is currently having a "bad day" (I also call them "zero days"), I wanted to make a small addition.
Sometimes I judge myself for having a bad day, and have a battle with myself: "common, get up and do something useful". There are days when I can win this battle and turn the tide, and thankfully I realized that I have a lot of tools for this - taking a walk with a dog, meditating, or even watching a TV show for an hour.
Still, there are days when it feels like I just can't win, and I realized that on those days, my inner critic becomes very upset with myself, and intensifies the "battle". However, then it becomes even more difficult to win. So, I decided I will do two possible things:
1. Re-set the day completely. Go back to bed, sleep for another 30 minutes. Brush my teeth AGAIN. Have breakfast, AGAIN. Do the whole thing, AGAIN. Very often, it helps me to restart the day and have a new day within this day.
2. Accept and let go of judgement. This can be very hard, but sometimes we think we have to be strong, no matter what, but I also realized that sometimes it is okay to have a zero-day, and to tell the world - "I need a day off, where I can just be lazy and do nothing.".
Usually, I get a much better day, after a day of lazy acceptance :)