I feel for you! I did this last year as well, earlier in year than you. Lost 4 stone with it, but towards the end was starting to struggle and had a few hiccups, then just gave up and ate and ate and ate - and I've put the majority of it back on - and put it on very fast.
Aside from feeling horrible anyway, what I did was so unhealthy.
So new year, new start. Planned on starting 2nd day back to work after Christmas - have learned 1st day not the day to try to start anything!! But horrendous situation at work and knew my head wasn't in right place to start, so finished out that week pigging away. Then in-law bereavement so involved with that for 3 or 4 days and like most Irish funerals, it all centered around food and drink.
So Tuesday was d-day. I've got through it, but found the first few days difficult. All I could think of was food, food, food.
I have motivated myself by doing a daily weigh-in - which I know not everyone agrees with, but it works for me. In the first week, I'm seeing daily changes, I know this won't happen after this week, but it's keeping me going.
What I'm finding most difficult is water! But as the week moves on I'm getting thirsty more which is helping. I'm probably getting 2 litres in every day and plenty black tea and coffee, but I want to get the water up more and the coffee down a little! Hard though when its cold.
I have to admit I feel better today than yesterday, Wednesday was the worst day for me, my head was just pounding all evening and night.
Best of luck with it and think of the results at 1st WI