Here's a good starting point.
http://www.mrmoneymustache.com/2012/01/13/the-shockingly-sim...
It's important to note that (Mustachian) financial independence isn't about making money so you can retire (despite the name). It's about designing a lifestyle for yourself that makes you happy without the need to buy things or experiences to sustain that feeling of happiness. The rest is just bookkeeping. And (as a neat side-benefit) you generally become healthier and fitter, gain more skills, and reduce your consumption levels, thereby helping save the planet.
Knowing that you're building a future life for yourself makes the hard days at work easier to take. Once you have the financial security of being FI/RE you are free to take career risks or try things that interest you but may not have much money-making potential.