India's Prime Minister Narendra Modi has asked world leaders to start a U.N. International Yoga Day. He was speaking at the U.N. General Assembly in New York. It was his very first speech at the 193-member General Assembly. He spoke about the benefits of yoga, saying it was good for the mind and body, and could also help climate change. He said yoga provides harmony between humans and nature, and is "an invaluable gift" from India's 5,000-year-old culture. Modi said: "It is not about exercise, but to discover the sense of oneness with yourself, the world and the nature." He added: "By changing our lifestyle and creating consciousness, it can help us deal with climate change."

Many doctors and people in the medical community say yoga is a good way to stay physically and mentally healthy. Yoga makes you focus on exercise, breathing and meditation. A lot of research says it can help people with heart disease, high blood pressure and lower back pain. Studies also say yoga can improve our mood, reduce stress and make us sleep better. However, there is also research that says people need to be careful when doing yoga. Wikipedia says: "An extensive survey of yoga practitioners in Australia showed that about 20 per cent had suffered some physical injury while practicing yoga." A World Yoga Day already exists. It was started by the world-yoga-day.org website in 2007.