Here's some recent news from the University of Southern California, where a huge clinical trial involving more than 110,000 women ages 20-79 has found that those who regularly engage in strenuous physical activity may have a lower risk of developing both invasive breast cancer and in situ (early-stage) breast cancer than women who aren't as active.

This information was published in the February 26 issue of Archives of Internal Medicine.

Why am I so enthused about this? Because this, ladies, is something we can control. We can't control our genes, or when we started menstruating, or a host of other risk factors, but we can control our level of physical activity and make sure we exercise enough to keep ourselves healthy.

Let's define what is meant by strenuous activity. Examples of moderate activity are brisk walking or playing a round of golf or a game of volleyball. Strenuous activity includes activities like swimming laps, doing aerobics, and running.

In the study, women who reported participating in strenuous activity for more than five hours per week over the long term (more than a decade) had a 20 percent lower risk of invasive breast cancer and a 31 percent lower risk of in situ breast cancer than women who participated in less than 30 minutes of strenuous activity per week.

Strenuous activity also appeared to be associated with a lower risk of estrogen-receptor–negative but not estrogen-receptor–positive breast cancers. Moderate physical activity did not appear to influence the risk of in situ breast cancer.

Is it too late to get your sneakers on and start moving? No! Just be sure to meet with your family doctor for a physical exam to make sure you are in good general health before embarking on anything too rigorous that is new for you.