Regular. Strenuous. Exercise. Memorize these three words. Live these three words. And abandon all thoughts of a fitness routine that is easy, moderate, or periodic.

Brisk walking, golf, and volleyball are considered moderate forms of exercise. Swimming laps, aerobics, and running are considered strenuous. And these are the activities we should be taking part in -- for the rest of our lives -- if we really truly wish to prevent breast cancer.

A new study, published in the February 26 issue of the Archives of Internal Medicine, shows women with a long-term history of engaging in strenuous exercise for more than five hours per week were 20 percent less likely to develop invasive breast cancer and 31 percent less likely to develop in situ breast cancer than those logging less than 30 minutes of strenuous exercise per week.

It seems strenuous exercise most affects estrogen-receptor negative breast cancer. But clearly, everyone can benefit from vigorous fitness training -- the American Cancer Society recommends moderate to strenuous exercise five days per week for at least 30 minutes each day -- and this is exactly why I am headed out for a run. Today!

Approximately 3 percent of all new cancers in the United States are linked to obesity, according to the US National Cancer Institute. Stay trim to cut cancer risk, that is what the headline reads. Researchers hypothesis that fat might be preventing apoptosis -- the process in which cancer cells perform a sort of suicide. But it's all untested speculation at this point as to how fat might affect cancer development and growth.

Recently, Rutgers University researchers conducted tests on mice and found leaner mice were less susceptible to developing cancer. Cancer cells in fatter mice died much more slowly, twice as slow as their skinny counterparts. The study is published in the National Academy of Sciences.

In other weighty health-related news, University of Pittsburgh researchers are reporting that overweight middle-aged people who walked briskly for 30 to 60 minutes a day lost 7 pounds in 18 months, while similar adults who didn't exercise consistently gained seven pounds in that time.

During the study, the participants were advised to eat healthy foods but not to restrict the amount of food beyond the norm. Seventy-five percent chose walking as their form of exercise.

Walking is a wonderful exercise for the body, mind and spirit. Most people do not walk alone, and this is a leisurely time to visit and enjoy each other's company. In addition, it's a way to slow down and reconnect with the world around you. Walking is a time to take deep breaths. Living Out Loud author Keri Smith, who blogs The Wish Jar Journal, often blogs about her many observances and adventures in walking and uses it as an exercise in creativity and a renewal of wonder in the every day. Delightfully, she collects things on her walk.

I am a fan of walking. Anyone can walk. During breast cancer treatments (except for the time my red blood cell count dropped so low I didn't have enough steam to make it across the room) walking was something I could do even if I did not have the stamina or will for more formal exercise.

It's no secret exercise is beneficial for just about everyone. So it should come as no surprise that researchers reported Monday that moderate, regular exercise can help women combat some of the side effects of breast cancer radiation treatment.

Researchers found that breast cancer patients who walked briskly 20 to 45 minutes three to five times per week during treatment maintained healthy blood cells. Red blood cells and hemoglobin -- which carry oxygen -- often suffer during radiation treatment. And those who do not exercise lose significant oxygen capacity.

This study, published in the journal Cancer, is the first to look into the effect of exercise during breast cancer radiation treatment. It rounds out research that already shows exercise can help prevent breast cancer and can also help women recover from the disease.