You just have to try and stay focused on your reasons for losing weight. There must be reasons why you reeeeally want to be slimmer...looks, health, confidence...etc. Try focusing on them, thinking about where you'd be now if you hadn't started at all.
I want to go on holiday with a friend of mine, can't wait to just park the child with my folks, jump on a train and go down south...feel independant and young and have some fun! That is keeping me focused because I really want to feel young and have some fun again.
I had my smallest loss so far last week and I was a bit pee'd off because I knew where I'd gone wrong and could have kicked myself. I've found that my routine is very important to me and a break in that throws me completely.
I was having "what's the point" thoughts for a couple of days and thoughts of thick buttered bread and lots of bags of my favourite crisps were creeping into my head. Then I stopped and thought about how crap I feel when I'm eating crap. Not only does my self esteem take a nose dive, I feel physically sluggish with no motivation to do anything. When I'm on plan I have more energy and a more positive outlook on things, which I'm really enjoying...just as much, if not a little more than the weight loss at the mo.
Don't give up, just think about your goals and what you've achieved so far and what you've got left to achieve, you can do it!!