Reset your happiness thermostat

The limitations we experience come from our belief system. It is strange that everyone wants to be happier, but when it comes right down to it, we often don't believe that it's possible. It's like believing that you can't make more money than you are making now. Something very simple happens when you have such a belief: You won't. It's as if we have an internal thermostat. It's set to a certain amount of money, and a certain amount of happiness. And as long as it's set that way we won't change much. [Source]