I've started to watch what I eat again. Due to circumstances I'm in (living at college), it doesn't really allow me to have full control over my diet - but I definitely have the ability to watch what I'm eating. What I've started doing is keeping a food journal - just a list of what I'm putting into my body each day at each meal. It helps a lot as far as motivating me to make better choices and of course keeping track of what I'm eating. Its easy enough to make a crappy decision if I'm not keeping track; I'll just eat it and not think about it again, but now I don't want to have to write it in my journal later on in the day, so I don't eat it in the first place.
I do plan on trying to overhaul my complete diet next semester, as I'll be commuting instead of living at school. I have moderate experience with nutrition (used to be super healthy in middle school / high school), and RC's plan is pretty damn good.