Sean Penn is one of the great actors of his generation, yet he’d like to give it all up to remain behind the camera. “It’s a good idea,” Penn said at the Toronto International Film Festival, where “Into the Wild,” his fourth directing effort, played in advance of its September 21 theatrical debut.

The Toronto festival is showcasing a big collection of films by actors turned directors, among them the filmmaking debuts of Helen Hunt, David Schwimmer, Gael Garcia Bernal.

On “Into the Wild,” Sean adapts Jon Krakauer’s best-seller about Christopher McCandless (Emile Hirsch), a young man whose bold, two-year trek around North America came to a tragic end in Alaska.

Sean, who also directed “The Indian Runner,” “The Crossing Guard” and “The Pledge,” said “Into the Wild” has strengthen his goal to one day give up acting in favor of directing.

“I’ve committed to act in a couple of things this year based on directors that I have great admiration for,” Penn said. “But yeah, this movie brings me to a place where I know what it is that I’m really looking for in making a decision about what I want to do as a director. So I feel more energized than ever in that way.”

What energizes Sean Penn and others to branch out beyond acting? Some say acting alone gets boring. I guess so… everything gets boring after a while. Some say directing can prolong their film careers in an industry where good roles dry up as actors age. Some say they just want to do it all.

To me, it seams like an obvious transition for an actor or actress. Instead of simply filing a role, the director must make each role fit together. This takes not only casting the proper actors, but making sure each character fits with the others and the set.