When it comes to making a decision that will affect your life as well as the lives of those around you, you should consider both the emotional and the financial impact. Numbers are important, but spending time with a young child or elderly parent can be much more valuable.
How will your decision affect others?
Think about those you love or who depend on you. Have you talked over both fears and hopes with your partner, family, and others who will be affected by your decision? What do you think the impact will be on each of them if you make this drastic change?
What is the best thing that could happen?
What do you hope to accomplish through quitting? What is your primary goal? These answers can give you hope and be your motivation during rough times that may lie ahead.
What is the worst thing that could happen?
What do you secretly fear and think about at 3 AM. Is your goal for which you are quitting work important enough to counteract your fears?
Do you have an "Exit Plan"?
Everything changes and sometimes you have to admit you made a bad decision. Have you thought out your success targets, failure points and how to determine when you reach them? (Other than running out of money, that is!)