In order to stay healthy, what must an animal's body do?

In order to stay healthy, the animal's body must maintain homeostasis. Homeostasis refers to the process that living organisms, such as animals, maintain in order to acquire a fairly stable condition that is needed for survival. The word "homeostasis" comes from the Greek words which mean

"Same" and "steady". This include in the control of body temperature, regulation of other physiological processes, management of stress, etc.