An endangered species is a species of organisms facing a very high risk of extinction. The phrase is used vaguely in common parlance for any species fitting this description, but its use by conservation biologists typically refers to those designated Endangered in the IUCN Red List, where it is the second most severe conservation status for wild populations, following Critically Endangered.
I measure my happiness 2 ways. 1  Through a (random and irregular) process of self reflection.  2 Catching myself being happy and remembering the last time I caught myself being happy and trying to determine the time between them.
But to Aristotle happiness means more than mere pleasure. Pleasure comes from the satisfaction of desires: getting what you want and wanting what you get. But happiness comes from the fulfilment of the person. And what is good for a thing, what leads to its fulfilment, depends upon what type of thing it is.