William is right that the brain circuits associated with pleasure and want are different. People are compelled to do things that are bad for them, whether this is a gambling addiction or trying to impress friends with a new car we can’t afford.

Humans also have the challenge of pleasure or happiness being defined in different ways. Will I get more pleasure from eating chocolate or going to the gym? Happiness is often seen as having a hedonic component of immediate pleasure as well as a broader component of life satisfaction. It means that, much as continuously eating cake might appeal to me, it isn’t enough for overall life satisfaction.