June 21 was the very first International Yoga Day, which was officially declared by the United Nations General Assembly on December 11, 2014. Spearheaded in India, the event seemed to be successful, with over 35,000 people attending a New Delhi yoga class.

In the U.S., some 20 million people practice yoga, touting its mental and physical benefits. Research has shown that yoga can reduce stress, improve depression and anxiety, and ease back pain, arthritis, chronic pain, and other chronic diseases like diabetes and heart disease.

New Delhi
Prime Minister Narendra Modi of India leads the largest yoga class in history on June 21, 2015. Reuters