BAKERSFIELD, Calif. -- People dealing with chronic illnesses such as cancer, heart disease, and arthritis often experience heightened stress and anxiety. They worry about medical bills, their future health, and being a burden to their families.

But the added stress takes a toll on their bodies, at a time when they need to focus their energies on healing.

There are drugs and psychological therapies available to help anxious patients, but a new study has found that simple exercise can have a big impact.

Researchers from the University of Georgia conducted a systematic analysis of 40 studies on physical activity training in patients with chronic disorders. The exercise programs averaged about 40 minutes, three times per week and included aerobics, stretching and weight lifting.

Results showed that participants typically improved their anxiety levels by 20 percent -- with longer workouts yielding a greater benefit.

The authors noted that exercise joins other alternative therapies, such as massage and relaxation training, which are also effective at reducing anxiety for weeks to months at a time.