A、It is also useful to get rid of a bad mood. B、It is too hard to do good to people’s health. C、It may boost the heart rate. D、I

Moods, say the experts, are emotions that tend to become fixed, influencing one’s outlook for hours, days or even weeks. That’s great if your mood is a pleasant one, but it will be a problem if you are sad, anxious, angry or simply lonely.
    Perhaps one of the best ways to deal with such moods is to talk them out: sometimes, though, there is no one to listen. Modern science offers an abundance of drugs. But scientists have also discovered the effectiveness of several non-drug approaches to make you loose from an unwanted mood. These can be just as useful as drugs, and have the added benefit of being nonpoisonous. So the next time you feel out of sorts, don’t head for the drug store—try the following approach.
    Of all the mood-altering self-help techniques, physical exercise seems to be the most efficient cure for a bad mood. "If you could keep up the exercise, you’d be in high spirits", says Kathryn Lance, author of Running for Health and Beauty. There is obviously a link between physical activity and mood changes.
    Researchers have explained biochemical and various other changes that make exercise compare favorably to drugs as a mood-raiser. Physical exertion such as housework, however, does little, probably because it is not intensive enough, and people usually do it unwillingly. The key is physical exercise—running, cycling, walking, swimming or other repetitive and sustained activities that boost the heart rate, increase circulation and improve the body’s utilization of oxygen. Do them for at least 20 minutes a session three to five times a week.