One of the most attractive features of cats is that contentment is their default state. Unlike human beings – particularly of the modern variety – they do not spend their days in laborious pursuit of a fantasy of happiness. They are comfortable with themselves and their lives, and remain in that condition for as long as they are not threatened. When they are not eating or sleeping, they pass the time exploring and playing, never asking for reasons to live. Life itself is enough for them > John Gray
(Whose new book Feline Philosophy is released in October.)
The above statement deserves a caveat. Any sudden change in circumstances, from climatic conditions to rearranged furniture can take them out of the contentment zone quite sharply.
And I know of umpteen ways to make a cat more contented.