The lower back is highly important towards keeping your posture consistent while walking and running. Without building strength in this area, you would be susceptible to experiencing pain within this region of your body.\
Here are some workouts that could help you build strength to keep your posture in tip-top shape.
Lie on your back on the floor (use an exercise mat if your floor is causing discomfort to the back). Bend the knees and place feet flat on the floor. Raise the hips until the body forms a straight sloping line. Make sure the gluteus is squeezed firm as your hips are in the air. Keep this position for 5 seconds before lowering the hips back to the floor. You may do this exercise in 3 sets of 15.
This exercise begins with you lying down on your stomach. Place your arms on your side. While squeezing the gluteus and contracting the lower back, raise the head, chest, arms and legs off of the floor. You may rotate the arms so that the thumbs are pointing towards the ceiling. Keep this pose steady for about 30 seconds before relaxing back on the floor for 5 seconds. Repeat this exercise 3 times.
Begin in a push-up position; however, bend the elbows and place full body weight on the forearms. Keep the body straight and the shoulders should be parallel to your ankles. Squeeze the gluteus and hold this position for 1 minute. Feel free to roll to the side and hold the body up with the forearm for 1 minute while keeping the body in a straight line.