I'm almost at 40 lbs lost with another 50 to go - here's how I'm doing it:
1. Follow the program. Making your own rules rarely helps.
2. Holy cow, journal, journal, journal - write down everything, it becomes easy to do and I frequently refer back to what I did weeks before and see what weeks had better weight losses.
3. Don't overwhelm yourself. I can't focus on the 50 lbs ahead of me, I'm only looking at the next five, and being excited about the last 40!
4. Have support. I tell people what I'm doing. At first I was embarrassed, but who was I kidding - they all could SEE me, they knew I was overweight. The truth is, everyone who knows I'm doing this, is going out of their way to help and support me.
5. Don't overdeny yourself. Resentment won't equal long lasting change. Make room for your favorite treats once in a while.
Best of luck to you!