Yoga is a great way to improve your posture, since it does great things for your spine. Practicing these postures regularly will strengthen your core muscles and help prevent back pain as well.
1. Tadasana (Mountain Pose)
Stand straight, with your feet touching and your arms a little away from your sides. Lower your shoulders and bring your chin back so that your ears, shoulders, hips and ankles all form a straight line. Breathe deeply in and out for a minute.
2. Uttanasana (Standing Forward Bend)
Start in Tadasana, then exhale and bend forward from your hips. Keeping your knees straight, you can either rest your hands on the floor in front of you, grab the backs of your ankles or just cross your arms. Each time you exhale, try to reach closer to the floor. Hold the pose for 30 seconds to a minute and then slowly come upward.