Exercise can help prevent many chronic illnesses as well as make it easier to manage health conditions, from diabetes to joint pain.

In terms of prevention, aim for the recommended 150 minutes of exercise, like brisk walking or cycling, each week. Along with eating a healthy diet, this can cut your risk of diabetes by more than a third, plus increase your level of good cholesterol. Exercise also lowers body weight, blood pressure and triglycerides, thus reducing key risk factors for heart disease.

If you're already managing a chronic illness, exercise may improve symptoms and reduce the amount of medication you need to take. It builds muscle, which helps you move more easily, and reduces stress, which can aggravate many health conditions. Back pain and arthritis improve with the right stretching and exercise plan. If you have diabetes, exercise can improve blood sugar control.

Exercise's health effects on:

Heart disease: Regular aerobic exercise and interval training in particular are heart-healthy, boosting cardiovascular fitness.

Back pain: Core exercises strengthen the muscles around your spine, creating better support for your spine.

Arthritis: Exercise enhances the muscles that support your joints, making movement easier; it also eases stiffness.

Diabetes: Exercise helps you use insulin more effectively and lower your blood sugar level.

Asthma: Exercise can help control attacks.

If you're managing an illness and haven't been active, talk to your doctor about what exercises are safe, any precautions to take, what kind of discomfort is normal, and what are signs to stop, like feeling dizzy, short of breath or chest pain.

Working with your doctor is especially important when you have diabetes. Because exercise can affect blood sugar, you'll need to take precautions to prevent blood sugar from becoming too low during workouts.

In terms of intensity, start off slow -- that means you should be able to talk, but not sing, when working out.