I have lower back ache and was informed by doctor that due bad posture (i have a little bulging belly and sitting work) I am having disc problem. I have started brisk walking to help me in attaining good posture and to shed some weight. And also doing certain exercises recommended by doctor. This has reduced pain in my back. Please recommend some exercises for strengthening my lower back muscles and also advice some weight training exercises which would help in my case. Thanks.