I just remembered how in the last season of Hataraku Mao-sama (the anime where the demon lord becomes a McDonalds worker) literally had a how to feel energy exercise for absolute mundanes. They taught Chio the bystander girl that caught up in the isekai war how to feel energy so she can send telepathic messages. It was about lying down in a hot spring and the head and the feet was above the water while the whole body was warm and they poured cold water on her head so she can connect that cold flow feeling from toes to the top of the head and move energy with that then she had to learn to shout loudly to learn to understand how you make your "thoughts heard".
I thought the anime is just some retarded dumb ass isekai writing as usual (mostly it was) but they portrayed a working exercise perfectly. Was wondering if the author got that from a tradition or he came up with it from his own.