Colleague Lee Eisenberg wrote a book several years ago called The Number. The concept was how much would it take for you to be able to pursue your dream, walk away from a horrible job or retire early? He has revisited this topic in an interesting column for Portfolio. I'm quoted, which is nice, but more importantly, it has some great interactive tools that allow you to take a look at what your comfort level is with money.
You can read it here:
Tell me what you think about this article in the comments section. What will it take for you to be comfortable?