"A lot of things happen when u exercise, even just walking that effects your body in every way," said Julie Badawi.
The American Cancer Society study followed more than 73,000 post-menopausal women for 17 years.
Study author Dr. Alpa Patel says the findings showed women who walked an hour a day reduced their risk of developing breast cancer by 14 percent.
"This was a moderately paced walk about a 3 mile an hour pace," she said.
While there is evidence exercise reduces the risk of many cancers, what hasn't been clear is what kind and how much offers the best protection.
Now, it appears even a moderately-paced walk can trigger a number of healthy biological mechanisms. It improves hormone levels, glucose metabolism and reduces chronic inflammation.
Dr. Patel says the research is very encouraging because many women find following an exercise routine daunting.
But a leisurely walk -- it's easy and inexpensive.
"We're not telling you to become a marathon runner we're telling you to simply go out and walk in the evenings or incorporate walking into your everyday life," adds Dr. Patel.
Good advice for everyone.