To alleviate low back soreness due to ongoing strain, you'll want to both stretch and strengthen, reducing wear and tear and bolstering your body's natural reinforcements.
Important physical factors for lower back health: 1) Hamstring flexibility. Tight hamstrings create a torque on your lower back, straining it. Increased flexibility relieves this strain. 2) Abdominal strength. The more stable your abs are, the more the lower back is protected. 3) A good stride resulting from the above two factors, as well as healthy feet. If you suffer from foot pain, your stride will be negatively affected, as will your posture when standing. This could increase your back pain. 4) A healthy weight.
See the following resources for some good ideas on flexibility, abdominal strengthening, foot health, and weight maintenance.