There's good reason to act like a kid this holiday. The physical and emotional release of being silly -- in addition to being just plain fun -- is a vital part of a healthy life. According to Ingrid Bacci, a mind-body healthcare consultant and author of The Art of Effortless Living, stress affects the muscular system and can cause it to tighten up, which makes you even more nervous and tense. Doing something silly encourages your body to let go. As your muscles relax, your mind relaxes, and so do your emotions.

"During the holidays, we tend to focus on all our obligations to family and friends, adding a burden on top of our regular obligations," Bacci says. "Inevitably, this makes us tense and angry underneath, even as we try to do things out of love. For a lot of people, the holidays are also a time of depression, a time in which they focus on what they haven't got, or on what they've lost. In either case, silly play takes you out of the dark mood."