It can happen to any one of us, your having a nice walk in the woods and your all of a sudden turned around and lost! The first thing I think I would be doing in that circumstance would be going into freak out mode and searching for something that I recognize.  Chances are that I would make myself more lost.  In the Webelos Castaway adventure it brings up a very helpful word, STOP.  The word stop is being used as an acronym. 
 

S

Stay Put! Don't do what my first reaction would be of running all over the woods getting myself even more lost.

T

Think! Use your noggin. When you are placed in a scary situation your going to have to calm yourself down to think more clearly and make rational decissions. 

O

Observe! Now that you are staying put and thinking, look around. You may need to find shelter for the night. There may be a water source that is near you that will assist you. Use your ears as people who are looking for you may be yelling your name.

P

Plan! How much food and water do you have in your ten essentials bag? Start blowing your whistle as soon as you realize you are lost. If you see storm clouds coming in, start building a shelter to keep you dry.  Before the hike, plan for the worst before hand.  Always have your ten essential ready!