Walking is the earliest and simplest from exercises. By putting one foot in front of other, you can start to walk your ways towards a healthier life-style. Walking is an easy way to challenge the cardiovascular system (心血管系统),while at the same time building muscles. But to achieve these goals, a little more than a gentle walk around the block is required. Walking actually burns as many calories (卡路里) as running the same distance - if done in the correct manner and at a reasonable pace (步伐). Start with a basic program that you can complete three or four times a week. This should include five main steps: -A beginning warm-up for about 5 minutes. -A little bit faster period of 5 minutes at medium level (中等速度). -A 10 minutes "burning" at a higher level. -A 5 minutes slow down period at a medium level. -A 5 minutes cool down period at a low level again. -A suitable walking pace of around 5 kilometers per hour will burn around 80 calories in 30 minutes. According to the passage, walking is a simple way to