"The mind is not a vessel to be filled but a fire to be kindled." Plutarch
"The brain is like a muscle. When it is in use we feel very good. Understanding is joyous." Carl Sagan
It's about brains, actually not breaking but shaping them, and, after all, that is what we are interested in. Contrary to old ideas, neuroscientists have discovered that adult's brains are constantly growing new neurons and connections. In this article (external link) are 33 ideas to keep it in good form. It misses doing jigsaw puzzles, but we all know this one ;-)