Thoracic mobility is a huge issue many people, including myself, have to keep working at. When you lose mobility in this region, you will often times develop shoulder dysfunction and even lumbar (lowback) pain. It can also be an underlying cause for cervical pain as well. This is an easy to do drill. The important key is to apply pressure through your knee into a foam roller/med ball. This locks your lumbar spine, which we want to keep stable, and allows the rotation to come through the thoracic area.