Liam Neeson "never leaves the house" without a survival kit.

The actor is currently promoting his new movie The Grey, which follows a group of men stranded in the Alaskan wilderness following a plane crash.

The star explained that while he enjoys being surrounded by nature, he likes to be well prepared for all eventualities.

"I love to be outside. I never leave the house without a Swiss Army knife and a compass," he told German magazine TV Movie. "When you're getting to your 60s every day is like a fight for survival. I often wonder why I'm in this world, what's my purpose and how long am I gonna be here?"

Liam added that it was tough to prepare for the physically demanding role.

He had to ease himself into the training required to manage in the extreme weather conditions on location.

The 59-year-old feels like his time for portraying such demanding roles is running out.

"It was hell. I never could survive what happened to these guys. I started with 20 seconds [of cold showers] and escalated to seven minutes. It immunises the body," he said, before adding that his physique is starting to struggle with such demands. "My knee and the right shoulder are making trouble. I give myself one or two years, after that I'm finished."

Liam discussed why he decided to accept his part in The Grey.

The idea of an outdoors adventure appealed to him because he enjoys a challenge.

"The idea sounded adventurous and awoke the young guy in me. I wanted to prove myself," he said.