Ever think standing was just a matter of keeping your body on top of your legs? It's hard to appreciate how involved a simple thing like just standing can be, how much concentration and how many subtle movements and adjustments it takes, until you take an Iyengar yoga class. Of course, the point is that you're not just standing. You're doing Tadasana, Mountain pose, and in yoga in the style of B.K.S. Iyengar, Tadasana is an active pose. B.K.S. Iyengar is one of the best-known yoga teachers and the creator of one of the most popular styles of yoga in the world. His style of yoga is noted for great attention to detail and the precise alignment of postures, as well as the use of props such as blocks and belts. No doubt part of Iyengar's success is due to the quality of teachers, who must complete a rigorous 2-5 year training program for certification.