Best cure for that is "do it every day for 15min a day!" From art, to meditation, it's exercise! (And I don't do this either, but I need to, and know it works from past experience.)
30% actually doing something productive.
10% seriously drawing, then getting mad at anatomy
10% eating / drinking / extend procrastination here / starving myself by concentrating too hard
50% procrastination
I've learned to stop being mad at art (doesn't help) and to just get through it. Writing is just a matter of taping my butt to the chair and doing it. Mulling around on an idea for a week just leads to me forgetting why I want that idea in.