Questions 1-3 are about the following passage.

    Everyone knows that exercising is good for you, but why? And how often and for how long should you exercise? Physical exercise is any activity that makes your body work. Taking a long walk, going on a bike ride, or taking an aerobics class can make your body work. Exercising makes muscles stronger, makes people better at many sports, and is good for the heart. Regular exercise prevents diseases such as obesity and diabetes. It's also good for your bones.

    Doctors say that the average person should exercise for thirty minutes every day, and this daily exercise should be cardiovascular. That means that while exercising, your heart rate should go up. Lifting weights, for example, is not considered cardiovascular. Although lifting weights is very good for your muscle strength, it does not keep your heart rate up for long enough.

    If your life is busy, you can do simple things like taking the stairs rather than the elevator. Walk to the places you need to go as often as you can. Exercise can be tiring and is not always the most fun thing to be doing. However, it's certainly the best way to keep your body healthy. You only have one body, so take good care of it by giving it proper exercise.