Steven Pressfield said this quote

“ Phobologic discipline is comprised of twenty-eight exercises, each focusing upon a separate nexus of the nervous system. The five primaries are the knees and hams, lungs and heart, loins and bowels, the lower back, and the girdle of the shoulders, particularly the trapezius muscles, which yoke the shoulder to the neck. A secondary nexus, for which the Lakedaemonians have twelve more exercises, is the face, specifically the muscles of the jaw, the neck and the four ocular constrictors around the eye sockets. These nexuses are termed by the Spartans phobosynakteres, fear accumulators. Fear spawns in the body, phonologic science teaches, and must be combated there. For once the flesh is seized, a phobokyklos, or loop of fear, may commence, feeding upon itself, mounting into a “runaway” of terror. Put the body into a state of phobia, fearlessness, the Spartans believe, and the mind will follow. ”