How aware are you of your own, both physical and mental, state during the day?
We all have worse days, catch colds and flu, get worked up over little things. The important thing is to be aware of our state, communicate it with people around in a mindful way, and take responsibility for our behaviour.
Next time you snap at somebody, don’t make a weak attempt to remedy the situation right away if you don’t feel like it. Let yourself cool down, catch a breath, and come back to them. I’m sorry I behaved yesterday this way, I was in a bad place, and I shouldn’t have acted this way.
Most of the time, it’s enough to admit your own weakness and being vulnerable. We are all humans, and being aware can only make us better at it.