Marcy and Jack take on a two thousand four chapter arguing appreciation is its own physiological mode — heart, breath, and brain locking into the same ten-second wave, measurably distinct from relaxation — plus a two-minute appreciation-locked morning practice. Read the paper: The Grateful Heart: The Psychophysiology of Appreciation (Rollin McCraty, Doc Childre, 2004, The Psychology of Gratitude, Oxford University Press) — https://www.heartmath.org/research/research-library/basic/grateful-heart-the-psychophysiology-of-appreciation/