If you are thinking of changing careers or possibly beginning a new business venture. You should do so while you are still employed. As much as you might be ready to abandon ship, you will find that once you are focused on new opportunities many of the skills acquired at your current job can help you on your new goals. Therefore while you are doing your research you can also be polishing your skills and acquiring new ones. See this step as a training process or self-development.
You are more attractive while employed
You take your mind off of the negative "doom" feelings and feel "empowered" toward change.
You redefine yourself which will reflect in your work.
This process will transform you and it will give you a new found energy that will be noticeable. You never know, doors might open up in your job which you did not even know existed. The opportunities are limitless once you begin redefining who you are and what you want in life.
If you choose to work in a job for the rest of your life, be it by choice not by settling for less than you want. You are too good and valuable not to be used to your full potential.