Four out of five Americans suffer from back pain at least once in their lives. After the common cold, pain in the lower back is the most common complaint that doctors hear.

Most of us hold a lot of tension in the back and neck areas, which leads to tightness. Pain and stiffness can result from any movement that is improperly performed. So any new activity that you are not ready for — that is, that you are not in shape for, or used to — can lead to back pain. This then causes the back to stiffen as a defense against further injury.

For example, you may have picked up a heavy object without enough support from the lower body, or you bent too quickly, perhaps to tie a shoe or turn on a computer, and the sudden shock caused your back to react with stiffness and pain.

Another common cause of back pain is our sleeping habits. For example, you may be sleeping on a mattress that is too soft or firm. Or you may be sleeping in a position that places undue stress on your back.

Here are two specific exercises for lower back pain that can reduce your stress. As you do each exercise, pay attention to proper form and don’t move any faster than you feel is safe.

1. Cork on the water. Lie on the floor, facing up. Slowly bring your knees up to the chest. Count to twenty slowly as you relax, keeping your knees in an upheld position. Allow your back to relax fully as you hold in place. You can picture the breath flowing into the location of the pain, then allowing the stress to drain from your back as you exhale. Take full, slow breaths.

- Variation: Do the stretch using one leg at a time.

2. Cat on the fence. Get on the floor, balancing your weight between your hands and knees. Now exhale and let your stomach arch toward the floor. Let all the air out of your lungs as you relax. Then inhale and let your back arch toward the ceiling. Hold your breath in this position, stretching out like a cat for eight to ten seconds. Repeat this up-and-down arching sequence for a total of eight to ten times.

- Variation: Do the same sequence, but use your wrists as a fulcrum. On the down stretch, point your pelvis toward the floor, and let your neck and head tuck in. On the up stretch, point your butt toward the ceiling, and let your neck and head stretch up too. Some people find it’s easier to picture this sequence as a snake arching out and contracting.

Some of the best exercises for lower back pain don’t feel like exercises at all: Aerobic exercise. Perhaps the easiest way to relieve lower back pain is simply to walk at least three days a week for a total of twenty minutes. Or if you like to swim, or ride a bicycle, or to wade in waist-deep water, then choose those activities to help you maintain back health.

If you increase your walking habit to at least thirty minutes, five days a week, you will gain the additional long-term benefit of improved cardiovascular health, one key to a long and healthy life. Choose a place you will look forward to walking, or even a variety of places to explore, and be sure to wear a pair of shoes that support healthy walking so that your feet and legs do not tire. You do not have to spend a lot of money for a pair of good walking shoes; a good shoe store can help you select the right pair for your walking habits. Investing in your long-term health is never a waste of time, energy, or money, and your back will thank you for it.