Several studies suggest that these changes through meditation can make you happier, less stressed -- even nicer to other people. It can help you control your eating habits and even reduce chronic pain, all the while without taking prescription medication. A quiet explosion of new research indicating that meditation can physically change the brain in astonishing ways has started to push into mainstream. Meditation is an intimate and intense exercise that can be done solo or in a group, and one study showed that 20 million Americans say they practice meditation. It has been used to help treat addictions, to clear psoriasis and even to treat men with impotence.The U.S. Marines are testing meditation to see if it makes more focused, effective warriors.