So is this a sudden deveoment?? If you feel like this is what you want and you are changing a life time of posture there are postural modifiers such as reverse wedg cusions to place you in a posterior pelvc tilt while seated. You could stretch the multifidus and extensors or the hip flxrs( is 1 tight others weak?) and xtend the thoracic spine in a variety of methods to decrease the extensor moment on the LS area. Consult a trainer In absenc of Sx , a therapist is really not needed