- all other factors being equal, there is a correlation between annual income and happiness (NB my guess is that this correlation only works within certain upper and lower bounds, but let that pass for now)
- the more sex you have, the happier you are (on average)
- increasing frequency of sex from once a month to once a week boosts your happiness to the equivalent of being given an additional $50,000 p.a.
- being in a healthy long term relationship = $100,000 p.a.
- men who paid for sex with a prostitute were considerably less happy
What do I think? That physical pleasure is good, and friendly interaction is good. Loving sexual relationships provide both of these, hence the positive correlation with happiness. Money can also help with both of these, so it is also correlated with happiness. But these are just averages: there are obviously other ways to get physical pleasure and to interact with others that are nothing to do with sex or money. However sex and money can be quantified (to some extent), and other routes to happiness can not, so they don't show up in surveys like this.