Believe it or not, stress is not the villain it's made out to be. In small, short-term doses, stress can give an athlete the competitive edge or a public speaker the enthusiasm to project optimally. It can even boost the immune system.

However, chronic stress over time—the kind commonly encountered in daily life, such as work overload, financial difficulties, marital problems—can have significant adverse effects on nearly every system of the body, suppressing the immune system and ultimately manifesting as an illness.

The danger occurs when stress becomes persistent and consistent, a way of life. Chronic stress raises the risk of viral infection and diabetes. It can trigger severe problems for asthmatics, lead to gastrointestinal issues and cause high blood pressure, which brings an increased risk of heart disease and stroke.

To get a handle on this silent adversary, you want first to recognize that you are chronically stressed. Here are four kinds of warning signs:

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