In part, doodling take the pressure of performance away. It's okay to accept imperfection. After all, you're just doodling.
I had also started to disconnect from the tangible aspects of art. I work mostly in digital mediums to the point where I had forgotten the joy of putting pen to paper.
One of the best things to help stir up creativity is to let go and experiment. To try things that aren't your style. To try your style in new ways and mediums.
For anyone who is interested in doodling as an art form, there are some great web sites and blogs. There is even a kit you can buy from Zentangle, with all of the supplies and how to's. For me, doodling was a flash back to middle school and filling in the time (as well as the page) while teachers droned on and on.