After a nationally televised panic attack, Dan Harris knew he had to change. A lifelong nonbeliever, he embarked on a strange journey with a disgraced pastor, a self-help guru, and brain scientists. He discovered that his biggest problem was the incessant voice in his head. Eventually, he found an effective way to control it: meditation, a practice once thought impossible or useless. Research shows it can lower blood pressure and even rewire your brain.