I've often wondered what it would be like to do something new every day of my life. It seems that if one were to try to live fully, one's intention would be to create new challenges, be it mental, physical or spiritual.
I recently picked up the book A Joseph Campbell Companion, Reflections on the Art of Living (edited by Diane Osbon) and was so struck by the quote, "The privilege of a lifetime is being who you are." It seems to me that the quest of a lifetime is to try to get closer and closer to that core.