The `Love & Other Drugs` star is concerned his acting career won`t always be successful but already has a back-up plan prepared for when he gets older.
He said: "You`re always wondering how long this will last. It`s a piece of being an actor. There`s always someone more talented or younger than you.
"But I also like to write. In years to come, I think that will expand. I won`t just be scrapping for the next job. Maybe I`ll create something for myself."
Perhaps Jake could consider penning his own comedy after admitting he accepted the role as a Viagra salesman who falls in love with a Parkinson`s disease sufferer - played by Anne Hathaway - in `Love and Other Drugs` because he was so tired of a lack of films that combined laughter and emotion.
He told Britain`s Glamour magazine: "I`m tired of comedies that make you laugh but you don`t buy the emotional side.
"The film has a sense of comedy, but also a sense of something deeper, about the difficulties of being alive."