1. You have so many projects you don't know which one to start first — so you don't start any of them.
2. Your important strategic business project continually gets derailed by urgent day-to-day business emergencies.
Projects are difficult because, by definition, a project is something you haven't done before - or haven't done quite this way before. This introduces risk and uncertainty. And since projects are undertaken to bring about something important and new, you don't want to risk failure. You need to protect your investment.
Often the reason you get project paraysis is because people treat project tasks just like other items on their to-do list. However, project tasks are special and different from your day-to-day "business as usual" duties. Project tasks are not isolated - generally they are done in coordination with other people or other events. The work that needs to be done to complete a project has to be planned and timed.
The tools and techniques project managers use are designed to reduce the risk and increase your project's success - so projects complete on time, within budget, and with results that meet your needs.