"Straighten your spine," whispered Jenny as she placed her hand on my back.

I loved this move, but could never do it right, even though I'd be practicing yoga on and off for about three years now. Something about it asked me to be too flexible, to vulnerable.

But I worked on flattening my back, all the same, and pulling my left shoulder back to deepen the stretch.

"Now, switch to the other side," said Jenny, in her steady voice, standing back at the front of the class.

I reached to the right this time and could hear the cracks emanating from my lower spine. I couldn't go as far on this side. I'm sure it has something do to with being left-brained. Being an engineer, twists aren't always the most structurally stable concept.