Every day, for 10 years, cartoonist Bill Watterson delighted readers with a new story in his beloved syndicated comic strip "Calvin and Hobbes." But that kind of round-the-clock ingenuity is no easy feat. His secret? Recharging the mind by letting it play. "I've had to cultivate a kind of mental playfulness," Watterson said in the same 1990 commencement speech at Kenyon College where he gave the quote above. "A playful mind is inquisitive, and learning is fun," he said. In other words, creative ideas come when the mind is encouraged to wander into new areas, exploring wherever your natural curiosity may lead. Instead of "shutting off" your brain at the end of a long day, reinvigorate it by indulging your innate sense of wonder. If you follow what makes learning fun, it's bound to lead you to new ideas.