The most difficult thing about acting and directing in a film is acting and directing in a film. Every ounce of your physical and emotional being, and your analytical and thoughtful and producorial being, is being exercised at all points. You are 100% working on overdrive, but because it is only for X amount of days, if you have the stomach for it, you hustle through. It's a massive undertaking, and I think preparation is the key to success for that endeavor.