"It will be hard to make a film worthy of this great man," Jolie tells PEOPLE

Angelina Jolie met Louis Zamperini, the 96-year-old former Olympic runner and World War II prisoner of war, last winter when she signed on to direct Unbroken, based on Zamperini’s life.

The pair became fast friends.

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“Angelina is a human dynamo, and I know she will tell this story in the right way,” said Zamperini, a bombardier who survived 47 days adrift in a lifeboat after a plane crash – only to be taken prisoner by the Japanese. Author Laura Hillenbrand’s biography, Unbroken, became a bestseller in 2010.

For inspiration, Zamperini bestowed Jolie a gold pendant in the shape of a running shoe – a prize from his running days – which she plans to wear during filming, which kicks off later this month.

Jolie says she only hopes the movie does him justice.