Asana

From Light On Yoga by B.K.S. Iyengar:

“Asana brings steadiness, health and lightness of limb. A steady and pleasant posture produces mental equilibrium and prevents fickleness of mind. Asanas are not merely gymnastic exercises; they are postures. To perform them one needs a clean airy place, a blanket and determination, while for other systems of physical training one needs large playing fields and costly equipment. Asanas can be done alone, as the limbs of the body provide the necessary weights and counter-weights. By practicing them one develops agility, balance, endurance and great vitality.”