After an Iyengar class, I know my body better. I have a better sense of alignment, of what my muscles are doing and how I can use them more efficiently.
In my most recent class, we learned about the four corners of our feet. The ball of the foot, right below the big toe, the other ball right below the little toe, and both sides of the heel. Now, draw an X connecting the ball below the big toe to the opposite side of the heel, and the ball below the little toe to the opposite side of the heel. Now, when you walk or stand or otherwise place your weight on your foot, try to press down evenly on that X on each foot. This will improve your balance.
While we take triangle pose, balancing on our feet, the teacher draws our attention to our hip sockets. Joint by joint, he talks us through adjustments. We can feel our balance improve, feel the femur slip more securely into the socket. When we wobble, he has us place an arm on a chair. I finally GET what yoga is about. It's not about looking like the pictures in the book. Very few people can do that. Yoga is about learning how your body works and how to make your body more stable and comfortable in all kinds of silly-looking positions, so you can live your life the way you want to. And as a bonus, my body feels deep down warmth after each class.