How does Parrado find the strength to continue his trek across the mountains towards civilization?

Parrado finds strength in his determination to survive and the hope of reuniting with his loved ones. The harrowing experience of the plane crash and the loss of friends fuels his resolve to push forward, driven by a sense of responsibility to not let their sacrifices be in vain. He draws inspiration from his memories and the will to live, which propels him to endure the grueling conditions of the mountains. Ultimately, his unwavering belief in the possibility of rescue keeps him moving towards civilization.