Tough cords called tendons anchor our muscles to our bones near the joints. Also, about 150 sacs of fluid called bursae are scattered throughout our joints to allow muscles, tendons, and skin to slide smoothly over our bones.

As we age, our joints become more prone to feeling the pain of tendinitis and bursitis, which can flare up throughout the body but have a particular fondness for the shoulders.

Though the bursae don’t change as we age, many peoples’ tendons become stiff and inflexible, much like dried-out rubber bands. When you overuse a muscle in an activity – like when you rake a yard full of leaves or hammer too many nails into a carpentry project – you can make tiny cracks in a tendon, leading to a painful case of tendinitis.

Excessive leaf raking can cause bursitis in your shoulder as well, either from too much friction rubbing directly on the bursa or from inflammation spreading it it from a nearby irritated tendon, he says. Either condition will make the area around your joint flare in pain when you move it, then quiet down when you rest it, though bursitis often has a more constant achy quality.

You should get medical attention if a joint suddenly becomes hot and painful and you can’t think of a recent exertion to blame. Though it’s rare, a bursa may have become infected by bacteria through a cut in your skin.

Over-the-counter medications like ibuprofen can help reduce inflammation and pain, but drugs are just one to solve the problem. Many people can heal their tendinitis and bursitis on their own if they follow some basic tips for resting the aching part and quieting the inflammation. But if a week or so of self-care hasn’t made your joint feel any better, see your doctor.