This nifty video shows how happiness is directly linked to your values, not the value of your things:

It's that simple: a life based on consumption means that not only do we use up Earth's limited resources, we are less happy and less inclined to help others, too. The big secret of happiness is that it can't be bought (or sold) – in fact, our best chance of being happy is to stop compulsively buying altogether. We might help save the planet, as well.