Bend your knees and keep your feet flat on the floor. This stretch is great for people who already have lower back pain. It stretches the lower back along with supporting muscles in the hips and glutes. Keep your other leg in a comfortable position - usually against the floor, either straight or bent at the knee. To add a hip-flexing element to the stretch, use your hands to rotate your leg by gently pulling your shin across your body.

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Write a summary of the previous text in Chinese:
在毯子上躺下，弯曲膝盖，脚平放。 保持这个姿势30秒。