First,there are many parts of our lifestyles which allow us to live healthily.For example,we all know about the importance of choosing healthy food and fitting enough exercise and physical activities into our daily life.Second,nowadays good-quality fresh food and sports facilities(设备) are available to us,so it should be easy to form healthy living habits. However,today there are also many things which prevent people from having a healthy lifestyle.First,industry and traffic have caused serious environmental pollution.What is more,we spend a lot of time sitting in the chair,and this often means we have little time for activities which can keep us fit.For example,there are many people who spend many hours sitting in front of computers working,studying or playing computer games.Besides,many people do not eat the right food.