Since then, LaBeouf has starred in many major films and television shows, including "Tru Confessions," "I, Robot" and "Holes."
"I didn't know anything about the craft [of acting] until I met Jon Voight … making 'Holes' with him. ... He broke it down for me. ... It's the biggest gift I've ever been given," he said.
He met Spielberg while working on "Disturbia" and since then the two have become close friends. Spielberg went on to cast him in "Transformers" and then chose him again for the fourth "Indiana Jones."
LaBeouf remembers getting a call from Stephen's assistant to come in on a Thursday "because Stephen doesn't do phone calls.
"I'm thinking I've done something wrong and I'm going to try and salvage my career from the shambles I've made it. ... It felt like going to the principal's office."
"I started smiling, grinning, sweating ... and then he said 'Indiana Jones' and I just went blank. ... I lost my mind," LaBeouf recalled with glee about the moment Spielberg asked him to be in the film.
"Indiana Jones and the Kingdom of the Crystal Skull" is the fourth adventure in the "Indiana Jones" franchise. It comes 19 years after the last Indy installment and reunited the film's creators, Lucas and Spielberg, along with its lead actors, Ford and Karen Allen, as love interest Marion Ravenwood.
LaBoeuf spent 4½ months preparing for the film, during which time he carried a switch-blade knife with him everywhere to get the hang of it. He also had to learn how to ride a motorcycle, use a whip, do extensive movie homework assigned by Spielberg, and gain about 20 pounds.
He recalled meeting Ford for the first time on the set as they were about to start shooting a motorcycle chase scene. "He came out of a helicopter he had flown in to the base where we were training. He flew it alone. ...This is Harrison showing up for work," LaBoeuf said, still in awe. "He gets out, walks around, reaches into the cockpit, pulls out his whip and gives us a Harrison Ford wave. ... He walks over, puts his hand on my shoulder and says, 'Are you ready to do this kid?'"
On that first day, as they got on the motorcycle together and started riding at 60 mph for a scene in which two trucks converge and they barely slip away, LaBeouf remembered worrying that Ford's high standards could do him in: "If he messes this up, we can always replace him."
Having apparently now won Ford over, as the cast chummily toured the Cannes Film Festival last week, LaBoeuf still looks in disbelief at his childhood. "He's John Wayne to me. ... He's the last cowboy."
Perhaps that is why movie-making can still feel like "it's all a game" for this hardworking, focused actor. Nonetheless, the Indy stint seems to have left him with a taste for risk and adventure.
He says he's simply looking forward to intimidating roles.
"That's the fun of it," he said. "If you're not nervous, there's no reason to do it."