The aquarium's resident octopus was a vigorous young female. When she'd first arrived, she had amused the aquarium employees with her various antics, her speed, and her uncanny ability to hide. Her tank was spacious and conveniently located, so she often had an audience, and she had seemed to like to perform.
As time went on, though, the octopus became less and less playful. She began to seem dull. Her handlers worried, but didn't know how to help. The octopus's physical health checked out, but her overall condition continued to deteriorate.
Then she stopped eating. Things were dire.
The aquarium folks sprang into action. Experts were consulted. The octopus, they hypothesized, needed more stimulation. They began giving her toys and puzzles to manipulate*, and she perked up a little. But she was still refusing food, and wasn't likely to survive her hunger strike much longer.
At last, someone had the clever idea to serve her daily rations in a locked box. Presented with a padlocked coffer, the octopus investigated, quickly popped the latch, and tucked right in to her dinner for the first time in weeks. The next day, same scenario: problem solved.
Reader, that octopus had nearly died of boredom.
Look, here's the thing: an octopus is a very intelligent creature. A member of the family cephalopod, it is considered one of the brightest of all the invertebrates. Octopuses have a very high level of dexterity. They use tools. They play. They have an uncanny ability to adapt. Studies have demonstrated that they have individual personalities. Much of octopus behavior suggests that they engage in meaningful cognition–which is to say: octopuses think. Their brains need to be occupied. They need things to think about, problems to solve.
In captivity and without meaningful engagement, an octopus can become bored, and a bored octopus cannot thrive. When its brain has no consequential work with which to engage itself, a captive octopus will tend either to become listless and resigned (as in the case of my friend's charge, this can spell death) or to make a nuisance of itself: octopuses have been known to break glass, to squirt visitors and handlers, to toss objects out of their tanks, and to instigate other such shenanigans.
Back to my friend the octopus intern, whose job it now was to keep this particular octopus occupied and in good health. This was, he explained, not an altogether straightforward task. Incarcerating her food in elaborately locked boxes did work, but after an encounter or two with any one lock, the octopus would have it figured out and lose interest. The locks on the food boxes had to be constantly changing, the challenges fresh. Otherwise, she'd get mopey and unruly.
So, what does this have to do with you?
Here's what I'm driving at: We humans are very similar. Our minds crave meaningful engagement. We are designed to struggle, to strive, to exert ourselves. We thrive when we have problems to solve, when we have significant work of one kind or another to do. Our great big brains don't tolerate idleness.
You've probably noticed about yourself or others that going unchallenged or uninspired tends to lead to restlessness, lethargy, agitation, and even depression. If you have children, you've almost certainly noticed that shiftlessness very often gives way to surliness, misconduct, and–my personal favorite!–the harassing of siblings. And if there are teens in your life, then you know very well that a rapidly-developing, challenge-craving young person, when she is not sufficiently engaged with her world and her work, may become apathetic, distressed, or disconnected, or she may exhibit behavior that is destructive to herself or others.