I heard once about a survey asking people how much more they would like to earn to feel comfortable. The prevailing majority answered that they would like to make about 20% more than they were making, regardless of if their current income was $20,000 or $200,000.

The key is in seeing our income in a human dimension. No matter how much we earn, there is only one dinner we can eat a day, one bed we can sleep in, one car we can drive at the moment, and so on. The key to our happiness with money is in noticing when money is no longer buying the necessities, but it stimulates our appetite for wealth.