For me, seeing my daily calorie deficit is very motivating. I agree that it can get addictive!
I also buy jeans in a smaller size and try them on occasionally, noting how they fit (or rather, don't fit) and how much better they are fitting over time. Once I am actually in that size, I get rid of the larger size so I have nothing to grow back into!
The easiest way for me to stay on track is to plan it, weigh it, log it, eat it. Oh, and I add in a couple of "free" meals a week so I don't feel so deprived and I have something to look forward to (just don't go overboard on the freebies).