Everyone needs a project in life (a la the philosophers in Sophie's World), hopefully something big and ambitious. What's yours?
I know mine. I started on it about 6 years ago, pursued it on-and-off for about 2 years, and then ignored it completely for the next 4 years, as I moved jobs. Now, I am on the threshold of moving into a new role, and I am filled with a determination to get back to my life's goal. One of these days, I will have done enough work on it to perhaps even submit it for a Ph.D. thesis.
When it's done, it will have a deep impact on traditional software engineering.