I have lost over 100 lbs with weight watchers.
Part of sticking with it is just setting it in your head that this is a lifestyle change, and not a diet. When you think in your head it is a diet it is harder but if you think, ok I am not going to make any changes that I can't maintain for life.
Exercise is something key for me. It keeps me going.
I can't give you many tips because it is just something that you have to decide in your head that you want.