The future holds many uncertainties, and your retirement is no exception: "What age should I retire?" "How long will I live in retirement?" "When should I start taking Social Security?" "How will rising medical costs affect me?" That's why planning is so critical, and a good plan will take into account many of the possible uncertainties. In the process of developing your personal retirement plan, it's important to map out these "what-ifs" - the scenarios, priorities, and choices that you'll build into your strategy.