Julia Roberts is amazed by how hard Tom Hanks works.

The actress stars with the actor in new movie 'Larry Crowne', and with the 'Philadelphia' star also taking on directorial duties, Julia was astonished by his energy levels and "impressive" command of the film.

She said: "It is funny with him directing, it's amazing the amount of energy he's emitting in a day. He must just go home and fall into unconscious sense of sleep. He really does go 100 per cent in each department. All day long he's happy, he's buoyant, he's present.

"It's kind of mind-boggling. This is only his second time directing, he really has it down how he can shape shift between one place to another, it's pretty impressive."

Julia believes Tom's desire to create a fun and collaborative environment on the film brought out the best in all the cast and crew.

She explained: "It was great, we both believe working should be fun, and I think we both believe in a responsibility to create that idea for everybody else.

"Tom is amazing at that, he makes everyone feel apart of it, participating in it, like their two cents are meaningful. It really is a collaboration. He really does create an environment where we're all happy and we feel like we are doing our best stuff, everybody."