It seems that not only Mormons or other religious people recognize the need for a rest day from rigorous training. And even when you're taking a weekly rest day, you can get burned out.
I found this article about the signs of overexercise. It also clarified for me while I find it so hard sometimes to take that rest day: the dopamine released when I exercise is addictive.
But also taking a break makes it easier for me to start again on Monday morning, not feeling worn out or burned out.
This article from "Runner's World" explains "Why you have to back off in order to push hard." The author writes,
Years of research disprove the notion that a day off wrecks fitness; in fact, the opposite is true. Little detraining—the loss of fitness and performance that occurs when you stop working out—happens until you take off more than two weeks. When it follows difficult bouts of work, rest lets your body adapt to the work and improve. ... Without recovery, adaptation may occur short-term, but ultimately it will fail.
I worked my butt off for six days to enjoy logging a zero on the seventh. I caught up on sleep and nursed soreness with massage and light stretching. The day was as crucial to training as a long run. I could push through hard workouts knowing rest was ahead. I started the new week physically and mentally restored—ready for whatever masochism awaited.And this one has five rules for not over-training when you feel like you just have to:
1. If it's physically or emotionally fatiguing, don't do it.
2. If it's in the name of fat loss, don't do it.
3. If it's explosive, don't do it.
4. If you don't want it specialized, don't do it.
5. If you have to warm up, don't do it.
Also, this author adds at the end: "Rest day training shouldn’t take more than ten minutes."
I really recommend this article --- the whole article, not just these little snippets I've included here --- for when you (I) are (am) tempted to do more than you (I) should. I needed that!