You need your spinal muscles to hold your posture. Posture muscles usually function without any thought. You do not need to think about balancing your body when you walk or bend, but if your postural muscles are weak you easily can hurt your back doing simple things like bending to pick up a shoe off the floor. You may need special training to help strengthen your postural spinal muscles to avoid recurring back pain.  Be careful when starting an exercise program. Doing the wrong exercise with a painful back may result in increased pain and spasm.