See this interesting article on how we really know much less about our (future) desires than we think.
Excerpt:
My favourite is a simple experiment in which two groups of participants get free sandwiches if they participate in the experiment – a doozie for any undergraduate.
One group has to choose which sandwiches they want for an entire week in advance. The other group gets to choose which they want each day. A fascinating thing happens. People who choose their favourite sandwich each day at lunchtime also often choose the same sandwich. This group turns out to be reasonably happy with its choice.
Amazingly, though, people choosing in advance assume that what they’ll want for lunch next week is a variety. And so they choose a turkey sandwich Monday, tuna on Tuesday, egg on Wednesday and so on. It turn out that when next week rolls around they generally don’t like the variety they thought they would. In fact they are significantly less happy with their choices than the group who chose their sandwiches on the day.
Also:
For example, how good would you feel if you won the lottery? Most people predict their lives will be completely changed and they’ll be much happier. What does the research find? Yes, people are measurably happier after they’ve just won, but six months down the line they’re back to their individual ‘baseline’ level of happiness.