Thank you for the link.

I think the discussion distinguishing like and want is the beginning of the answer. My view is that there are a number of distinct complementary motivations which can cause subtly different emotions, each of which can be referred to as happiness. With each motivation having evolved because it contributes towards our survival. These distinctions become clearer when trying to create enjoyment experiences and I'll elaborate on my take on them in the next article.

What I think is so interesting (and important) about this is that without understanding why we are motivated (and made happy) we cannot accurately make predictions of human behaviour or indeed form a meaningful utility function that is based on enjoyment. In this way deciphering human motivation is essential in order to apply reason to our lives.