Even if you have had horrible posture for most of your life, you can still change it by taking the right steps today. Yoga can be a valuable tool in correcting a long career of bad posture. The following video shows a simple exercise that strengthens all of your erector muscles (the muscles that run beside your spine), interscapular muscles (the muscles that pull your shoulder blades together), and your lower trapezius muscles. Strengthening these muscles can result in a straighter, stronger back, and a reduced slouch.