Get ready to meet the Hollow Body. Yes, you read that right. The Hollow Body is an isometric exercise (meaning it holds tension without much movement) that involves adopting a position similar to ...

according to the Vogue interview, is Dr Bronner's Almond Pure-Castile Liquid Soap. "I wash my body in it. I wash my hair with it. I washed my clothes in it," the rock star admitted.