The woods might symbolize a place to test your willpower, but it could also symbolize the unexplored or unknown, and the forgotten. I would make this comparison because the forests often are associated with being lost. Also in a society full of technology, it could be easy for a human to disregard the complexity and beauty of nature, causing it to become an unknown, unexplored and a forgotten place. Woods are also a harsh place to live and survive using survival skills thus testing your willpower to survive. Forests are also vast and diverse, making them easy to get lost in.
These are things that I believe the woods symbolize.
cheers!
