Some people can just sit still and be entertained; others will go stir crazy without something to do.

I never saw it as a problem myself. If I got bored with the scenery and the bird-watching, I'd probably try making up some math puzzles. (My dad spent several days in a POW camp in Italy reconstructing the proof for the Pythagorean Theorem that he'd learned in university.)

I'm told that it's more likely to be a problem with children of a certain age group (8 to 14) because they often have a lot of energy and a limited attention span. Even though they may know about the "hug a tree" principle, they may be conditioned to think that if they stop and hug a tree, rescuers will magically pop up from behind the nearest rock; after 4 or 5 hours with no sign of rescue, they may get bored and/or start panicking and decide to try exploring a little further "just in case".

I agree with Moine, a couple of feet of paracord (and, if possible, a good book on knots) would provide many hours of amusement.