Very useful, thanks. Basically: "your age to retirement depends entirely on your savings rate, as a percentage of your take-home pay".
So, in short, try to live on less, put the rest in the bank and don't spend it. Live on what you need, avoid needless luxuries. And avoid credit card debt like the plague, right?
http://www.mrmoneymustache.com/2012/01/13/the-shockingly-sim...
I found it provided a very useful perspective.