Over-stimulation (like heavy schedule/marathon grading/time-consuming and focus-required activities)

Lack of sleep

Life stressors (not necessarily directly about me - can be my kids or husband)

All three I've learned to manage more deliberately and stay proactive about which has helped immensely. I'm less likely to just let these things happen to me like I used to which helps. If I can see them coming, I can manage them. If I can't see them coming, it's a bigger challenge, but I do have plans of action that keep their impact down a bit.