In Britain, doctors now use exercise as a first-line treatment for depression, but it’s vastly underutilized in the United States, and that’s a shame. According to the World Health Organization, depression is the leading cause of disability in the United States and Canada, ahead of coronary heart disease, any given cancer, and AIDS. About 17 percent of American adults experience depression at some point in their lives, to the tune of $26.1 billion in health care costs each year.
