When you're in pain, exercise is probably the last thing on your mind. But it may be more important than you think. Regular exercise is a versatile weapon in the fight against chronic pain.

When you're inactive, your muscles — including your heart — lose strength and work less efficiently. Your risk of high blood pressure, high cholesterol and diabetes increases. Inactivity can increase fatigue, stress and anxiety as well.

"Years ago, people who were in pain were told to rest," says Edward Laskowski, M.D., a physical medicine and rehabilitation specialist and co-director of the Sports Medicine Center at Mayo Clinic, Rochester, Minn. "But now we know the exact opposite is true. When you rest, you become deconditioned — which may actually contribute to chronic pain."

As tough as it may be to start an exercise program, your body will thank you. Are you skeptical? Consider the facts. Exercise can:

• Prompt your body to release endorphins. These chemicals block pain signals from reaching your brain. Endorphins also help alleviate anxiety and depression — conditions that can make chronic pain more difficult to control.

  "Endorphins are the body's natural pain relievers," Dr. Laskowski says. "Endorphins have the potential to provide the pain-relieving power of strong pain medications, such as morphine."

• Help you build strength. The stronger your muscles, the more force and load you'll take off your bones and cartilage — and the more relief you'll feel.
• Increase your flexibility. Joints that can move through their full range of motion are less likely to be plagued with aches and pains.
• Improve your sleep quality. Regular exercise can lower your stress hormones, resulting in better sleep.
• Boost your energy level. Think huffing and puffing through a workout will leave you wiped out? Not likely. Regular exercise can actually give you more energy to cope with chronic pain.
• Help you maintain a healthy weight. Exercise burns calories, which can help you drop excess pounds. This will reduce stress on your joints — another way to improve chronic pain.
• Enhance your mood. Exercise improves blood and oxygen flow to your muscles and contributes to an overall sense of well-being. Looking and feeling better can improve your confidence and self-image as well.
• Protect your heart and blood vessels. Exercise decreases the risk of high blood pressure, diabetes, heart attack and stroke.

Consult your doctor for help designing an exercise program that meets your specific needs. Your doctor will likely recommend various stretching, strengthening and aerobic exercises. Swimming, biking and walking are often good choices. Exercises that help you relax — such as meditation and yoga — may be helpful, too.

It's natural to be worried about hurting yourself or making your pain worse. But with your doctor's reassurance and guidance, you can safely exercise with the knowledge that your pain isn't serving a useful protective purpose. Remember, regular exercise actually eases chronic pain for many people.

Even if you recognize the benefits of exercise, staying motivated can be a challenge.

"Remember to start slowly," Dr. Laskowski says. "Don't rush into a strenuous workout regimen before your body is ready. Consistency is more important than intensity — especially if you have severe pain."

It's also helpful to build your exercise program around activities you enjoy. Exercise with a friend or join a class at a local fitness center. As your energy increases and your mood improves, you may actually look forward to exercising.