Jon.  I like your approach.  Finding your purpose starts by living a life of purpose.  As we serve our families, networks, and communities, our purpose will begin to surface.  It's like passion.  Some people look for their passion as though it's a gold nugget buried in some river bank.  The better idea?  Get passionate!  Whatever is in front of you this day, please be passionate about your involvement with it.  The result?  Your passion becomes more clear.  And so does your purpose.