The solution

Standing, swaying on the subway home, I'm surprised by the lately rare blossom of depression, right in my solar plexus, something like pain.

As soon as I get home, as quickly as I can, I change clothes, feed the cat (who meows plaintively, demanding attention and food), and get my yoga mat down on the ground. 

I lay on my back on it and, as soon as the bell announcing the beginning of the session rings, feel the knot of anxiety and sorrow begin to unravel itself. I breathe deeply and move through the postures, grateful and growing happier with every breath, as the cat stalks around my few square feet of peace.