A Willingness to Experiment
Young children love to explore and experiment. If they can't eat something, then they'll try to break it. If it won't break open, then maybe it'll flush down the toilet. Life becomes a series of entertaining and informative explorations into the unknown. If you hadn't been an intrepid child explorer yourself once, you'd never have learned that fire is hot. You'd never have discovered that all dogs aren't friendly or that turnips aren't nearly as fun as they sound.
Experimentation is good. It helps map the frontier. It makes the world more knowable, more interesting and more immediate. Break out of your rut and experiment a little. Learning new things will help your brain stay active and healthy into old age. Kids learn important things by experimenting, and so can you. Just because you've reached your prime doesn't mean you know it all.