Four steps: that is the distance from the wall where a vertical plank of wood is affixed to a movable stand. My yoga teacher instructs me to place the heel of both hands in line with the point where the plank and stand meet. I curl over like a cat to ensure the back of my head is flush against the plank. If the distance is correct, I can walk both feet up the wall behind me, transforming my body into an L shape with the rear of my skull, back, and sacrum all touching the plank. I must resist the tendency to flare out my rib cage by engaging my abdominal muscles and tucking in my tailbone. Phew – I’m sweating already, just from keeping my body in the correct position. But the real work hasn’t yet begun. The challenge is kicking one leg up into a fully vertical position while maintaining the alignment.