After returning from deployments in East Timor and Afghanistan, Corporal David Cantley suffered from anxiety, depression and panic attacks.
But creating and acting in a play about stories from the front line has changed his life.
The former Unanderra resident was part of a collaboration between the Australian Defence Force and Sydney Theatre Company to create The Long Way Home, opening at the Illawarra Performing Arts Centre on Wednesday.
The play features 12 defence force personnel and four actors telling the stories of servicemen and women who have been injured or struggled with psychological problems from their operations in Iraq, Afghanistan and East Timor.
Corporal Cantley, who plays a psychologist and soldier, said military training had taught him to be tough, so he hid physical and emotional problems that later affected him.
"While you're trying to put on a brave front, it's another battle inside," he said.
"The main thing that helped me [during the play's creation] was to talk.
"It's changed my whole life completely."