The swap happened mid-set, somewhere between the clang of dumbbells and the hum of the air-con. One blink I was spotting my gym partner—then the room flipped sideways. When the haze cleared, the barbell on the rack was lighter, my centre of gravity all wrong, and the reflection staring back wore her training gear instead of mine. It wasn’t just a trick of perspective; I was in her place, living her rhythm, hearing my own voice come out of her throat. Across the floor she stood inside my frame, wide-eyed, both of us realising we’d traded without asking.

We tried everything: swapping equipment, retracing steps, even shouting for help, but no one noticed. The world simply accepted that I had always been her and she had always been me. I went through the motions of her routine, the mirror showing my familiar face on her shape, sweat slicking skin that didn’t quite feel like mine. When the session ended, I caught her—my old body—smiling back with a mix of shock and envy. The forced exchange wasn’t ending soon, and somewhere in the confusion was the smallest whisper of curiosity: what would it be like to live the other half of our shared effort?