一个人发生任何疾病,都有它的内因和外因。体内各器官功能低下,不能抵御病菌的侵入是生病的内因。外界的微生物(病毒、细菌)、化学物质(药物)、还有光、温度等物理因素是生病的外因。要减少疾病就要从这两个因素入手:开展体育锻炼,增强体质是战胜疾病的内因,搞好环境卫生、饮食卫生、个人卫生和安排好作息制度等是战胜疾病的外因。身体锻炼能提高体内各器官的功能,因 A person has any disease, it has its internal and external factors. In vivo organ dysfunction, can not resist the invasion of bacteria is the internal cause of illness. External micro-organisms (viruses, bacteria), chemicals (drugs), and light, temperature and other physical factors are sick outside. To reduce the disease should start with these two factors: to carry out physical exercise, physical fitness is to overcome the internal causes of disease, improve environmental health, food hygiene, personal hygiene and arrangements for the system of rest is the external cause of disease. Physical exercise can improve the function of various organs in the body, due to