The lights are dimmed, candles are lit, bodies begin to sway together as the voice from the stage says a spirit-lifting, soul-stirring affirmation…and then screams “Now sprint for 10!”. Group fitness classes have, for many, become something more than just a good way to get the blood pumping and pounds dropping. On this episode we take a look at why exercise classes from Soul Cycle to Crossfit have become some of the most fervent venues for secular spirituality and how some religious leaders and institutions are re-discovering this age-old symbiosis of body and spirit -- ones that use the body to change what we feel, how we connect, and what we believe. And we'll learn some of the science behind why sweating together brings us closer together. Episode Guests: Casper ter Kuile is the author of the book The Power of Ritual. Find out more about his work on his website. Emma Cohen is a Professor of Cognitive Anthropology at the University of Oxford, where she leads the Social Body Lab. Rabbi Jaymee Alpert is the co-creator of Neshama Body and Soul, a practice that combines exercise with prayer.