A Lasting Mark

Today I was reading in Joshua about the 12 stones chosen for the 12 tribes set as an alter.  The words that stuck out in particular were "and they are still there this day".  It got me to thinking, what do I put my efforts toward that will leave a lasting mark?  What impact am I having that will affect the world for years to come?  It is such a different way for me to think.  I often think of relationships with people that I know have had a large impact, even an eternal one at that, but I don't often think about what I will leave behind.  I think about how to help people in their here and now.  I guess I don't think that's necessarily a bad thing.  I'm beginning, and I mean at this very moment, to think about what it is God is asking, or has asked, me to do that will leave, or is leaving, a deeper mark.  Just food for thought today.