Asana is the “yoga” of American yoga: the physical poses. Some forms of yoga don’t even have a physical practice, but they aren’t the forms you find at the gym or parks and rec. Although there are eight limbs in a traditional Raja Yoga approach, Modern Postural Yoga generally puts asana first.
Asana is a valuable part of yoga, but not because it burns calories (although it does) or because it makes you more physically flexible (although it does), or even because it builds strength (although it does). Asana is useful in regulating mood, healing discomfort, and correcting physical problems caused by a busy life. Snap at the kids? Back hurt from hunching over a computer? Worried about what your body will look like in 10, 20, 30 years? Asana helps.
HOWEVER, the real value of asana for the Type A practitioner is being in the pose. Learning how to let go of who you are and what you have to do and just existing in the present moment is priceless. Many of us spend all day curled up in the recesses of our brains, but asana allows us to take ourselves into the body. For one brief moment, all of the emotional and intellectual storms inside and the storms outside just disappear.