Why not start out with something simple like a blog. You can get a free account at Blogger and write about whatever you like. It will help sharpen your writing skills and it may help you with your focus. Make a goal to post 3 entries per week.
A self help book? What would your advice be exactly?
You always seem to have so many ideas but you go for the BIG ideas right off the bat therefore nothing gets done. First it was the BA job, then the expensive scooter club and now writing a book.
Take your BIG idea and simplify it so you can accomplish it. If writing intersts you start your blog tonight. They are free, very easy to set up and it will at least give you an attainable focus for this latest idea.