If you have joint problems, simply opening a jar or climbing stairs can cause pain. Vicious cycle: When it hurts to move, you may stop exercising — yet moderate exercise eases joint aches and stiffness by increasing strength and flexibility and decreasing inflammation. Solution: With your doctor’s approval, try the exercises below.

STRETCHING makes joints more limber, prevents muscles from becoming short and tight, and protects against injury. Stretch gently, moving each joint to the maximum range of motion possible without causing unusual discomfort. Do these moves daily, working up to 15 repetitions of each.

Shoulder stretch. Sit with back straight and clasp hands behind your head. Move elbows forward as if trying to get them to touch in front of your face. Hold five seconds. Next, move elbows back until they point out to the side… hold five seconds. This increases shoulders’ range of motion — making it easier, for instance, to style your hair.

Bathtub stretch. Moist heat eases movement by increasing flow of blood, oxygen and nutrients to joints. During a warm bath or while seated on a shower stool, “circle” wrists by rotating hands, envisioning fingertips tracing the face of a clock. Next, circle ankles by rotating feet.

Finger flexion. Bring the tips of your right thumb and forefinger together, making as round an “O” as possible… hold five seconds… repeat with other fingers. Switch hands.

RESISTANCE TRAINING strengthens muscles that surround joints, easing pain by providing muscular support. Try these exercises three times weekly, building up to 15 repetitions of each.

Hand helper. Hold a tennis-ball-sized foam (Nerf) ball in one hand… squeeze, hold five seconds, release. Switch hands.

Hip extension. Lie facedown on a mat or bed, legs extended. Bend arms and turn head to one side, resting your cheek on the backs of your hands. Knees straight, raise your right leg until your ankle is eight to 12 inches above the mat… hold five seconds… lower. Switch legs.

Knee extension. Sit in a chair, feet flat on floor. Raise your left foot, straightening knee completely so the leg is parallel to the floor… tighten knee and thigh muscles… hold five seconds… lower foot to floor and relax. Switch sides.

Foot and ankle strengthener. Sit in a chair. Place your bare foot on top of a tennis ball on the floor. Bearing down slightly, roll the ball underfoot, using the muscles of the toes, arch and ankle to move the ball back and forth and side to side. Continue for 30 seconds. Switch feet.

AEROBIC ACTIVITY, such as walking, rowing and stair-climbing, burns calories and helps you lose excess weight that stresses joints. For sore shoulders: Swim in a heated pool. For problem knees and hips: Try biking or stationary cycling. Build up to five 30-minute sessions weekly.