Exercise amount more important than intensity

I read today in newspaper that Exercise amount is more important than intensity: "How much you exercise may be more important than how hard you exercise in terms of heart health, according to a study of sedentary overweight men and women. And, many will be happy to hear, exhaustive amounts of exercise are not needed for heart health. In journal CHEST, researchers from North Carolina report that people who walk briskly for 12 miles per week or for about 125 to 200 minutes per week will significantly improve their aerobic fitness and lower their risk of developing heart disease."