I've been trying to unravel this for a while, so it seems like it belongs here.
In short: I experience acute depression when doing gym classes that involve work on the floor. Pilates, yoga, certain conditioning classes - they all send me into a downward loop. I'm lying on the mat trying to concentrate on my form, or on the instructor's directions, but really I'm slipping away. I'm comparing my life to others' and finding it deficient and I'm slinking slowly towards something that feels dangerously like a panic attack. It was so bad last week during a class, that the instructor came over and spoke to me. She thought I was having difficulties with the exercise, but, really, I was just paralyzed by despondency.
The stupor lasts for 10-15 minutes after I'm off of the floor.
I don't understand it. I can do yoga on the floor of my living room with no problems. I can do crunches at the gym by myself with no sadness. After the depression washes away, I'm always a little confused as to why it happened and why I was so sad about things that are either not that important to me or are completely someone else's idea of success. I feel wrung out like a dishtowel, a little exhausted and careful with myself. I catalogue all that is right in my life, as if to throw the earlier misery into sharper relief.
I get runner's high, so maybe it's only natural that I get Pilates low.