I agree that checking up on this website, and tracking my weight has been a motivator for me.
My family has a number of health issues that I have inherited and that alone is a big motivator for me to be as healthy as possible (not to mention I'm on a dr. recommended diet, and am on drugs where weight gain is a side effect...ugh).
Having friends to talk about diet/exercise with has helped me immensely. One of my friends told me that my goals shouldn't be X amount of lbs down (though it's still okay to track that) but more like X amount of exercise per week, and X amount of days where I follow my diet to a T, and any weight loss, even the smallest loss, should be treated as a bonus victory.
This mindset has been my saving grace. I went from plateau to losing weight again, based on this mindset, and I feel like it keeps me from punishing myself and then getting depressed and binging, or getting to obsessive/extreme with cutting cals, etc.