One Sentence

I'm currently reading the book Drive by Daniel H. Pink. The book is about motivation, and at one point in the book he talks about what makes great men and women. President Kennedy's was once told by Clare Boothe Luce, one of the first women to serve in the U.S. Congress, that "a great man is one sentence." Rather than splinter our lives off into various purposes, it serves us better to orient ourselves toward a greater purpose. So, the question is, What's my sentence?