Keep your heart healthy. Women who exercise about 2.5 hours per week are 25 percent less likely to have heart disease later in life, according to a 20-year study published in the American Heart Association's journal Circulation. Researchers analyzed exercise habits and heart health of more than 97,000 women.
Avoid diabetes. Another 20-year study, at the University of Minnesota, found that being fit reduces the risk of diabetes. It found that exercise reduced risk even when people gained weight as they got older.
Stay mentally sharp. Exercise protects against Alzheimer's disease and other types of dementia. It's especially beneficial after age 75, according to a study of 3,700 men and women at the University of California, Los Angeles.