Muscles tighten during the course of the day, and when you feel stressed out, the process accelerates. Stretching loosens muscles and encourages deep breathing. One of the greatest stress-relieving stretches is a yoga position called the child pose, which stretches the back muscles. On a rug or mat, kneel, sit back on your heels, then lean forward and put your forehead on the floor and your arms alongside your legs, palms up. Hold for one to three minutes.