Actor Leonardo DiCaprio learned a lot about acting on the set of The Revenant, because he had to use his eyes and face so much to convey emotion.
The 41-year-old has won a Golden Globe and a Critics' Choice Award for his performance as frontiersman Hugh Glass in the critically acclaimed Alejandro Gonzalez Inarritu film.
DiCaprio admits the gruelling shoot pushed him as an actor because he had very few lines.
"I knew this was going to be somewhat of a silent performance; that's part of what was exciting," he told Variety.
"But more than anything, I think I learned a lot about being an actor on this movie. It has a lot to do with trust.
"Trusting the people you're working with, giving yourself over to a unique process, and trusting that if the people you're working with are committed, like Alejandro, you can focus on being in the moment and rely on your instincts and trust the journey."
Production took place in freezing cold temperatures in Canada and Argentina and DiCaprio was required to walk around in the snow wearing a 120-pound (54kg) bear skin for many of his scenes.
Even when times got tough, the star still found great joy in the experience.
"There were so many monumental undertakings in this film," he explained.
"We could talk at great length about the bear sequence, the horse sequence, the bison sequence, the rapids sequence, fighting with Tom Hardy, who is like a bear in his own right, but most of the stuff was so meticulously planned out.
"We would rehearse all day long, and every single department needed to work like a Swiss watch. It was like creating a small play every day, and doing live theatre for an hour and a half in natural light.
"Sometimes it was just: 'Glass walks up a hill' - and the bear fur weighs 120 pounds wet, and I'm freezing my a*s off, and it became some of the most difficult stuff to do in the movie."
His hard work has definitely paid off.
DiCaprio is the front-runner to win the Best Actor Oscar - his first - at next month's Academy Awards.