Cardio for Your Heart
All healthy adults ages 18 to 65 years should engage in at least 150 minutes of moderate cardio training per week or 75 minutes of vigorous exercise (or a combination of both).
Moderate-intensity activities: These make you feel like you're working "somewhat hard," but you should be able to talk while exercising. Examples include brisk walking, swimming moderately, or cycling on level terrain.
Vigorous activities: These really challenge you and feel "hard" due to your more rapid breathing and greatly elevated heart rate. Some examples are race walking, jogging or running, water jogging, bicycling uphill, gardening with a shovel, or playing competitive sports like soccer or lacrosse.
Intervals: If you're just doing mild ("fairly light") or moderate activities, you can increase your fitness by doing intervals: simply increase your intensity for short periods. For example, while walking, speed up slightly for a short distance before slowing back down to your original pace. Continue to include these short, faster intervals occasionally during workouts and, as you are able to, lengthen the intervals so that they last up to 1-2 minutes at a time.
Caution: If you've been mostly sedentary, start with mild or moderate exercise and progress slowly to higher intensities to avoid injuries, loss of motivation, and potential cardiovascular problems!
Brisk walking and other mild and moderate activities are generally safe to start on your own, but if you want to do vigorous activities, it's recommended that you see your health care provider first just to be on the safe side.