I'm nothing without my music. Turn off the tunes and I can't run as fast or bike as powerfully; I can't relax on a plane or enjoy a car ride. We've all felt it: calm music slows our heart rate; fast tunes jazz us up and motivate us to move. And it's scientifically proven to be a powerful fitness tool -- like a jolt of caffeine, with a melody. Here's how the right music can amp up your workout!
A version of this story originally appeared on Self.com.