So I'm shooting with a 50D and a 28-70 Tammy. Not the heaviest setup, but not the lightest either. If I zoom in and aim one of the focal points at a vertical line, it bounces in and out of the focal point. I want to be able to hold the camera rock-steady. I've tried repositioning my hands and bracing my elbows against my torso. Really though, I think I need some sort of exercise to train my body to be steadier. Any suggestions for exercises?