I keep track of my calories, but I have a history of not being able to regulate my weight by just 'winging' it.

I've lost 95lb since the spring of 09 and have kept it off by keeping track of my calories. Not really difficult to do. At night, I plan out what I will have the next day. I have my food logging program on my phone or web based during the day if I need to make changes 'on the fly'.