A word for persons who won't advance or improve [closed]

I'm looking for a word to describe a person or persons who are comfortable in their state of being or their position in life, who are unwilling or afraid to change for the better or even take a chance. I once read a book with the word in it, but I can't remember what it is.


Solution 1:

Complacent:

showing smug or uncritical satisfaction with oneself or one's achievements (Oxford Dictionaries)

Content:

satisfied with a certain level of achievement, good fortune, etc., and not wishing for more (Oxford Dictionaries)