How can a yoga posture or time spent watching your breath change the way you feel? Our brains are plastic, and engaging in a behavior over and over again leads to changes in our brains. Neuroscientist Sara Lazar shows us, through magnetic resonance imaging (MRI) of the brains of study participants, that yoga and meditation are effective in reducing stress, reducing symptoms of diseases such as depression, insomnia and anxiety disorders, and, interestingly, increasing quality of life - people report that they are happier.