The best of luck to you this time.
I've re-started countless times, and re-joined the local slimming club at least a dozen times, always telling myself 'this is the time'.
This time, I've changed a few things about how I would normally go about things, for example I got an exercise bike to save me making excuses about the gym, and I paid in advance for three months at the slimming club so that I have an incentive to go each week.
I'm hoping that the changes, plus increased motivation will get me past the 4-week barrier into some real progress.