It would seem that I read Infinite Jest during a period of my life when I was superstitious about marking up books. I now see that in the entire 981-page novel (or 1079 if you include the footnotes, which, of course, you should), there are only two brief passages that I underlined. The first: "Be no one."
It is easier than you think.
The second, on the very next page: "Managed fear."
As you have probably heard, Wallace is dead by an apparent suicide. A Newsweek reviewer said it best: "I suspect that Wallace was a genius who happened to be a writer, rather than a writer who happened to be a genius."
Update: His recent commencement address is worth reading.