I work for a company that offers an incredible benefits package at a very competitive rate. This and high moral is what has kept me with my employer for the last 4 years 4 months, and 14 days (who's counting?). There are many other factors to it, but those are the two that stick out most (I should not have to mention salary).
Seriously though. I feel that if a company is going to invest that much into making sure I'm healthy and happy, then I should make sure they know that it is worthwhile investment. Hence the tenure.
A conclusion is simply the place where someone got tired of thinking.