One of the things that helps keep me motivated is my fiance, the fact that she's going through it too. Her being on a similar diet helps so much with the joint decisions we have to make, and I try to push her to get her to come to the gym more.
For me, the biggest motivation, I think, is accountability. A lot of times, people are very secretive about their weight, despite the fact that it's right there for everyone to see. While gaining weight, people will sneak food off by themselves a lot, hide under baggy clothes, do whatever to avoid the judgement of others. In changing my lifestyle, one of the main changes was to become transparent in my habits. I post here... I'm on board with my fiance... pretty much all of my friends and family knew about my trying to lose weight before they got to notice it physically. That creates accountability... if your friend Steve knows you're all about losing weight, and he sees you for the first time in a couple months, and you look the same, or bigger... your failure is on display for everyone. But when you do well, everyone will tell you how great you look and how great you're doing, because they know the subject isn't off limits with you, and this drives more motivation. It can be hard to motivate yourself to work hard in the gym on Thursday, November 12th, 2009 because you want to look good for your wedding on May 8th, 2010. It's stilll so far away it's abstract. That's a final exam, you can prepare for that at the end, but you have to be prepared for the little pop quizzes along the way.
Everyone gets craving and temptations, but once you get used to a healthy lifestyle, even for just a few weeks, it gets so much easier. I have allowed myself to eat whatever I want on rare occasion, maybe once a month. And I've adapted my favorite foods to be more healthy. I love spicy food and used to love Chipotle burritos. Now I make them myself, with a wheat wrap, fat free refried beans, Perdue perfect portions chicken breast, fat free Kraft shredded cheese, salsa, and Cholula hot sauce, and lettuce. My fiance likes sweets... now she makes sugar free jello pudding all the time, and we recently went to Coldstone and got their Sinless Sans Fat Sweet Cream Ice Cream with blueberries. These substitutions may not sound quite the same, but when you're not assaulting your taste buds with fast food everyday, the simple things start tasting better.