Developing a character from your notebook

She is small, but not fragile. Her body is strong, muscular, but not obviously, because she is all rounded and mellow-looking. She is pretty too. Not beautiful, no. At least, I don't think so, like I don't think I am beautiful. Her face has the same roundness her body does, the roundness that makes her look nice, cozy, and innocent. You know the face, with a shy smile and dark eyebrows above hazel eyes, all these framed by dark long hair. But it's as easy to imagine a nasty expression on that face as it is to see her smile.
Her expression is empty now, as if she is seeing something far ahead of her. But now and then, I glimpse a stray slant look she casts across the gym at a stout man panting at one of the machines. She has earphones on, like many of us here, but I bet there is no music there, as she is as aware of her surroundings as one can possibly be. When I passed behind her back, I knew she noticed me.
She is not new here, for it is easier for her to do the same exercises than it is for me. She pulls more weight, and without too much effort, which is strange, because she is so tiny and toy-like. But I still see her exhale with as much energy as pleasure, and her silky glistening skin tells me she is here not just to pull wool over someone's eyes.