Won't feel so confident when you become irritable, your training goes to shit, you start losing sleep, you get sick all the time and so on...

Could be as simple as taking a day off training and just going on a long walk or doing chores around the house. It's a rest day where you use your free time to do something vs taking a day off where you do no real physical activity.

Like what the other person said. Stay active, but don't do any formal (or at least stressful) exercise. Gentle NEAT is better than being sedentary (unless you're severely ill or injured).