It's documented that he went to the doctor in August 2002 at the urging of his dentist, which is when he was diagnosed with cancer. After the diagnosis, he instructed his PR person to generate as much publicity about his terminal illness as quickly as possible.
My Shit's Fucked Up was actually released two years before his cancer diagnosis on the album Life'll Kill Ya. Several of the songs on that album did end up being prophetic two years later though.
TheResurrection OP t1_iu9ymic wrote
Reply to comment by Rhindressduo in This weekend is the 20th anniversary of Warren Zevon's final appearance on the Late Show with David Letterman by TheResurrection
He actually lived another ten months after this performance, well past the period of time to live that the doctors had originally given him.