Yoga is known for stressing how breath aids in movement. The same principle applies to Pilates. Too anything in life. If you're not breathing you're not moving. When in doubt breath more.
Close your eyes while taking in a few deep breaths right now and see how much lighter you feel. Breathing is the body's natural way to get rid of toxins and fuel you cells with clean oxygen so they can work more efficiently. This is a principle we don't think very much about even though it is cued throughout class.
We take for granted that our body will breath on its own. However, when we take in a full breath that really fills up the lungs we are using more muscles and able to take in a greater amount of air. This allows for effortless movement that looks more graceful. Breath in through you nose and exhale out your mouth. Take a moment to get in touch with the rhythm of your body during you next Pilates session.