THE LIGHTS TURN OFF just before I close my eyes. And now I'm in complete darkness on my yoga mat. I'm tuned in to the rhythm of my breaths during a calming box-breathing drill – inhaling and exhaling on a four-count led by instructor Tyler White – feeling my lungs and chest expand. It's the way I wish I could feel at the end of every workout.
Except as I take a peek at the two pairs of dumbbells
