No excuses! The time to work out won't just fall in your lap. You have to make the time. The American Cancer Society recommends that you get at least 45 to 50 minutes of exercise five times a week to help lower your breast cancer risk. The American College of Sports Medicine recommends that all adults under 65 at least do moderately intense cardio for 30 minutes a day, five times a week, or vigorously intense cardio for 20 minutes a day, three days a week, to lower their risk of disease and keep their hearts healthy.