You save up to buy your first used car, then as soon as you've driven it for a while, you think how nice it would be to have a new one. You get the new one, and think how much nicer it would be were it a specced-up Mercedes. By the time you get the Merc, you're ogling the Ferrari. This sense of wanting more and not being satisfied with what was so wonderful last week is called the hedonic treadmill, a term coined by the Nobel prize-winning psychologist Daniel Kahneman. Women get it with handbags (the high of the It handbag lasts all of three days), and children get it with PlayStation games. Happiness is not achieved by acquiring bigger and better, newer and more expensive toys, though we all want them anyway. Seeking the cure has become the holy grail of psychology, though it seems that shooting downwards - eg, expecting and wanting less than you can afford - is one way around it. Of course, this becomes a stalemate rather than a treadmill, because if you don't really want something, why go out and buy it?