Exercising may not be a top priority for women who’ve just been through treatment for breast cancer.  But doctors say staying active is critical to beat the disease.

Susan Brown is the managing director of health and mission program education at Susan G. Komen Breast Cancer Foundation.  She says “the largest study to date followed survivors over five years and found that one to two hours of brisk walking per week was associated with 40 percent lower risk of early death overall compared with those who were less active.”

A 2011 meta-analysis of studies found that mortality rate for breast cancer was 34 percent lower for women who were very active, when compared with women with breast cancer who weren’t active.

Still, a study from last year found that breast cancer survivors weren’t meeting U.S. exercise recommendations.

Brown says someone who is in active treatment may not feel like walking nine hours a week, but even walking a small amount of time can help with increased energy and fighting depression.