Breath: the new science of a lost art, by James Nestor (book; helped me switch fully to nasal breathing, practicing better posture, warm myself when I'm cold, a

Breath: the new science of a lost art, by James Nestor (book; helped me switch fully to nasal breathing, practicing better posture, warm myself when I'm cold, and breathing with my whole torso rather than just belly) Becoming the Iceman: pushing past perceived limits, by Wim Hof (book, but I've only listened to his breathing exercises for warming the body)