You might think you have back problems, but you might be wrong. At least half of my clients over ten years of personal training have seen their back pain disappear as we went after the real culprit - the hips!
This is very often the case - a client works at a desk, sits in a car, then sits on the couch. Any time you sit in a regular chair, you are contracting the hip flexors - the muscle group that brings your thigh up closer to your stomach. This group becomes hypertonic - always ON. So when this tight hipped person tries to stand upright, the hips remain tight and so the lower back arches to allow the motion of standing. The psoas, a particularly strong flexor, actually wraps from the front of the hip to the lower back, so if it is tight, the pelvis becomes tilted forward and the lower back automatically stays in an excessive arch.
Good stretches for the psoas and hip flexor group are a runners lunge and a spinal twist.
And stay out of chairs!