(CNN) -- Asked about part of the entertainment business he particularly enjoys, Greg Behrendt -- stand-up comedian, author, TV writer and producer -- had an unusual answer.
Greg Behrendt co-wrote "He's Just Not That Into You," based on a popular episode of "Sex and the City."
"My instrumental punk and ska band called the Reigning Monarchs," he said with a laugh. "There's seven guys in the band. ... We play shows around Los Angeles."
But the co-author of "He's Just Not That Into You," now a film starring Jennifer Aniston, Scarlett Johansson and Ben Affleck, admits that stand-up comedy remains a longtime passion. In fact, it led -- in a roundabout way -- to "He's Just Not That Into You."
"I was a stand-up who had an HBO special called 'Mantastic,' and it was directed by Michael Patrick King, who became an executive producer of 'Sex and the City,' " Behrendt said.
One thing led to another, and Behrendt soon joined a mostly female writing team on "Sex and the City." He observed that he was the only straight male writer for the show and offered the group valuable and realistic insight into the world of men.
"Sure, I felt a little bit like a token," he said. "It's not like those women needed my help, but I think there are days when you can't write in a perspective you don't live."
That perspective, along with colleague Liz Tuccillo's female point of view, gave way to "He's Just Not That Into You." The book is based on a popular episode of "Sex and the City," in which Carrie's boyfriend (played by Ron Livingston) offers the line to Miranda as she puzzles over a date.
The book is a wake-up call for women who obsess and worry about relationships, with an overarching message that if women find themselves doing the chasing, it's likely the guy simply isn't interested.
"We were raised to pursue women. ... Most of the guys I know enjoy the pursuit," he said. "But that doesn't mean women should be wallflowers."
As a comedian-turned-relationship expert -- one who is, by the way, now happily married and writing a book with his wife -- Behrendt said he hoped women would realize their worth when they read the book or watch the film.
"[Women] deserve great things, and they get to decide what their relationships are, and not other people," he said. "You often hear women say, 'I don't know if he's ready to get married.' Why are you waiting for his decision? We always put our fates in other people's hands."