"If you fail to plan, you plan to fail." This maxim, often attributed to Benjamin Franklin and likely the cause of many a teenage eye-roll when enduring a lecture about the evils of procrastination, is so ubiquitous you'll even hear it on a Taylor Swift single. That doesn't mean you shouldn't pay it any heed, particularly when you're thinking about retirement.

Dr. Rui Yao, Director of Graduate Studies and the Director of International Financial Planning Initiative at the University of Missouri, stresses that failing to plan is the biggest mistake most people make. "People love to dream about what they will do when they finally do not have to work, but they hate to do the math. Ironically, retirement is too important a financial goal for people to make mistakes on. We can put off a vacation if we make a planning mistake, but once we retire, it is impossible to start over."

According to a recent survey from the Transamerica Center for Retirement Studies, many workers report having a financial strategy in place for retirement, although nearly half of them (43%) don't have that plan written down on paper. Only 34% of surveyed workers say they have a contingency plan if their original one fails for any reason.