Yoga is a physical, mental and spiritual practice aimed for attaining permanent peace within. This practice for permanent inner peace originated in Ancient India and it also belongs to the six schools of Hindu philosophy or six "astika". Yoga is also considered as a form of exercise because of its physical forms and postures that has physical benefits to the body and it is also considered as meditation because of the mental and emotional benefits it gives as well as it is also considered spiritual because it involves getting in touch with your spirit or beyond physical nature. This is why yoga is known as a combination of physical, mental and spiritual exercise and development or creating union with your inner self which can benefit life. Это и многое другое вы найдете в книге Yoga for Beginners (Samons Brittany)