When it comes to weight control, almost nothing is easier and cheaper than brisk walking. Going for a walk every day can (47) mood, increase energy, lower blood pressure and (48) against a list of diseases including cancer. But to (49) these benefits, you need to get the lead out and put some spring in your step. It’s not window shopping or taking a stroll in the park. Walk like you’re late for the bus. You should be able to carry on a conversation, but you’ll be a little (50) when you talk, says Miriam Nelson, director of the John Hancock Research Center on Physical Activity, Nutrition and Obesity Prevention at Tufts University in Boston. You should be able to feel that your heart (51) is up. One study found that people who wear a pedometer (计步器) walk about 2, 000 more steps a day, or about another mile, than those who don’t. That burns about 100 (52) calories a day. Another study by Harvard scientists showed women gain an average of 20 pounds over 16 years as they move into middle age, but those who (53) walk briskly or bike are less likely to gain as much. Still, other research shows that both men and women get (54) health and weight-control benefits from doing both strength training and regular aerobic (有氧的) (55) like walking, biking, jogging, swimming and dancing. "Even a little physical activity is better than none at all, but more physical activity (56) greater health benefits, especially when it comes to weight control," Nelson says. A. activities B. balance C. breathless D. equals E. excess F. extra G. improve H) prevent I) protect J) rarely K) rate L) reap M) regularly N) substantial O) tired