Here is a nice article I just had to link to. It describes how people can be content with what they got and not only "when the big thing happens".
An interesting detail is a TED video, embedded in the page, in which Dan Gilbert talks about happiness. It shows the research results data about hapiness of lottery winners and paraplegics one year after the event. The information is quite interesting and educational. Have a look.
In the comments there was an interesting link, too: http://www.newdream.org/