A new survey measured the time spent behind the scenes, and found that, on average, people spend 34 hours of their lives untangling holiday lights. Here are some other results: We spend more than 2 days of our lives decorating Christmas trees. A day-and-a-half picking up or vacuuming pine needles from living trees. Two-and-a-half years planning and preparing the main holiday meal. 164 weeks . . . or just over 3 years . . . preparing for guests to arrive.