We're all asymmetrical to a degree, but there are acceptable ranges of asymmetry. As a javelin thrower, I had to address this problem, but pre-hab is relevant to everybody; it will make you more powerful, and help avoid injury. To see how asymmetrical you are, get a stopwatch and lie on the floor on your side, raise your hip off the floor and push up so that your weight is on your elbow, your forearm and the outside of your foot. Ensure your body is straight, and hold the position for as long as you can, timing it. Repeat on the other side and if the times aren't within 10 or 20 seconds of one another, you've got muscular imbalance. To redress it, do exercises such as side-bends or stretches.