American Cancer Society (ACS) recommends we get out there and move our bodies because physical activity may reduce the risk of several types of cancer:
Breast
Colon
Endometrium (lining of the uterus)
Prostate (advanced cancers)
The risk of other cancers may be lowered as well, although, right now there is less evidence.
A physically active lifestyle may also lower the risk of other health problems - such heart disease, high blood pressure, diabetes, depression and osteoporosis (bone thinning).
And we all know that being active helps prevent weight gain and obesity.