Jason Lim the 2007 to 2008 fellow at Harvard Korea Institute says it essentially boils down to two fundamental insights of the nature of existence.
The first component is the insight of transience, or impermanence. In other words, it means that everything that has a form is bound to decay, die, and disappear eventually. Nothing remains forever.
The second component, which follows upon the first, is the insight of selflessness. This is trickier to comprehend for selflessness is not unselfishness; instead, selflessness is a state of being. You exist at this very moment in the state.
He adds that "once you really internalize these insights, you will be awestruck with absolute humility and desire to serve others because it actually means serving yourself".