原文：There are several reasons why people choose to become vegetarian. Some do it for ethical reasons, believing that it is wrong to kill animals for food. Others do it for health reasons, as vegetarian diets are often associated with lower rates of heart disease and cancer. Still, others choose a vegetarian diet because of environmental concerns, believing that meat production is harmful to the planet.

重述：Becoming vegetarian is driven by various factors. Ethics is one of them as some people believe slaughtering animals for food is morally wrong. Health is another factor with many associating vegetarianism with lower rates of cancer and heart diseases. Furthermore, environmental concerns are leading some people to adopt vegetarianism since meat production is viewed as doing harm to the planet.