You can always tell when it’s going to rain. You feel it “in your bones” hours or even a day before it pours. But lately you feel as if it’s raining every day. Each morning, you wake up to red, swollen and stiff limbs. And every day, your activities are limited because of the pain and lost motion.

Like nearly 43 million other Americans, you have arthritis. To protect yourself against the pain, you may have limited your activity — especially exercise. This is a common response. But this is harmful rather than helpful.

Over time, reduced activity will cause your joints, ligaments and muscles to lose range of motion. Muscles may even shorten and tighten, increasing pain and stiffness and keeping you from doing the things you enjoy. But you can minimize your pain and loss of motion.

First, you need to work with your doctor, rheumatologist or other health care professionals on a custom treatment plan, which will be based on your type of arthritis (there are more than 100 types), the severity of your symptoms, the joints that are affected and your age, occupation and everyday activities. Treatment programs often include rest, exercise, medications and physical and/or occupational therapy.

One of the most beneficial ways to ease arthritis pain is warm water exercise. The soothing qualities of warm water, in combination with its buoyancy, make it an ideal exercise environment.

Immersing in warm water raises body temperature, causing your blood vessels to dilate and increase circulation. Also, warm water is easy on the joints and muscles. It promotes muscle relaxation, while supporting your joints to encourage free movement and to build muscle strength.

Initially, you’ll probably work with a therapist before exercising on your own. When you aren’t exercising with a therapist or an aquatic exercise instructor, be sure to exercise safely.

For example, make sure the water is at the appropriate temperature before you begin (hot tubs can get dangerously hot). If you start to feel lightheaded or nauseated, get out of the water immediately and carefully.

If swelling, stiffness or pain increase, stop and check with your doctor; never perform aquatic exercise during or after drinking alcohol or using drugs. Pregnant women should talk to their doctor first before beginning a warm-water exercise program.

Once you begin the program, remember to submerge the body part you’re exercising, and begin and end with easy exercises. Start slowly and don’t overdo it.

Be sure to move your joint through a complete range of motion, if possible. But don’t force movement, and stop immediately if you feel pain. Pain that lasts for more than two hours after exercise may be a sign of over-exercise.

Do 10 repetitions, as tolerated, or whatever your therapist recommends. Here’s a few sample exercises you may be asked to do, depending on which joint(s) is affected:

— Walking.

— Leg swing. Stand with your left side against the pool wall, place your left hand on the wall for balance. Bend your right knee and bring your thigh parallel to the water surface. Straighten the knee, bend it again, then lower with the knee bent.

— Arm circles. Raise both arms forward until they’re a few inches below the water level. Keep elbows straight; make small circles (size of a softball) with your arms. Gradually increase the size until they’re the size of a basketball, then decrease again.