When I first found out John Edwards would continue campaigning for the presidency even though his wife's cancer had returned, I was shocked, to say the least.

What was even more surprising was that Elizabeth Edwards encouraged her husband to continue and vowed to help him with the race, just as she had done all along.

Elizabeth Edwards was first diagnosed with cancer in 2004, but she was treated with chemotherapy.

Her breast cancer is now back in an incurable form, classified as stage four and lodged inside her rib. Doctors have given her only a 50-percent chance of surviving five years.

Why isn't she at home resting? I couldn't help but wonder.

How could John Edwards keep on campaigning when his wife might only have five years to live?

Then something struck me -- a medical expert interviewed on the news said that it's good for Elizabeth to have a purpose and goals to achieve.

It could be what keeps her healthy longer.

Days later, America was given another shocking announcement -- White House Press Secretary Tony Snow's colon cancer had returned, and this time it had spread to his liver.

But instead of cowering in the corner, Snow said he plans to fight his cancer and return to work.

The incredible optimism of Snow and Elizabeth Edwards prompted me to think more closely about the power of positive thoughts.

Can positive thinking really have an effect on the body?

According to research on www.webmd.com, optimists are more likely to overcome pain and adversity, and mental and emotional expectations can influence medical outcomes.

In general, people who are happy and have a purpose tend to live longer.

Researchers at Yale University found people with an optimistic outlook lived 7.5 years longer than those with a gloomy view of what lies ahead, according to a Newsweek article from 2005.

Another scientific example of how the mind can affect the body is the "placebo effect."

A placebo is a drug or treatment that provides no medical benefit except for the patient's belief that it will help.

Many patients who receive placebos say they feel relief from their medical problem, even though they did not receive actual medication.

More research on the mind-body effect needs to be done, but the power of positive thinking seems to be a hot topic in the health field nonetheless.

A simple Google search using the keywords "positive thinking" and "health" yielded 975,000 results.

And Elizabeth Edward's and Snow's optimism about returning to work and looking toward the future has only brought more attention to the subject.

In light of the Edwards's decision to continue campaigning, The New York Times ran an article last week about families who choose to work when they must fight serious illnesses.

According to the article, while some families said they have to continue working for financial reasons, many said they do so out of the need to be positive and carry on as normal.

The article also cited a 2006 survey of households affected by cancer conducted by USA Today, the Henry J. Kaiser Family Foundation and the Harvard School of Public Health.

The survey asked if cancer had caused the patient or someone else in the household to lose or change a job, work fewer hours or have a lower income.

The vast majority of people, nearly 80 percent, said no.

Elizabeth Edwards won't stop living her life because of cancer, and she said in a recent interview with The New York Times that she expects to live a long time.

"My feeling is, if we gave up what we have committed to as our life's work, wouldn't I be getting ready to die?"

It seems Elizabeth Edwards and Tony Snow are making the choice to live.

You may say it's not that easy, but a positive outlook could just be the medicine they need.