In our culture, men tend to define themselves by what they do professionally. Often, women define themselves by their roles or relationships. Linking your role to your mission places you in a vulnerable position because your role is likely to change most notably through death or divorce. Your mission is not your To-Do List. First, there is a huge distinction between what is important and what is urgent.
Most people fill their to-do lists with activities which appear to require immediate attention.
When writing your mission statement, contemplate the big picture and focus on your core values. Develop your mission first, then list corresponding goals. Otherwise, you can be very busy following a to-do list without creating anything worthwhile. You are already living your mission on some level. Living your mission may not require massive changes.