There's no question that planning is an integral part of lives. We schedule everything from meetings at work to haircuts and dentist appointments. But did you know that scheduling leisure activities like happy hour can actually make them less enjoyable? According to a series of 13 studies from the Olin Business School at Washington University in St. Louis, leisure, once scheduled, becomes more like work. That causes people to become less excited by and even resentful towards such scheduled leisure. In the end, people enjoy such activities as going to a movie and grabbing a bite to eat much more when they're unscheduled. It makes sense that we would derive less pleasure from activities we've jotted down in our planner or smartphone calendar. Think about it: We've all made plans ahead of time, only to blow them off because we weren't in the mood or just didn't feel like standing up and getting dressed. On the other hand, if a friend proposes that you g...