Welcome back to Slimming World AmbHaims! I can absolutely relate to your story, I joined a few years back and lost my way after a while, which meant I quit. I ended up gaining back all the weight I lost and then some. Some time passed and I rejoined in September feeling as motivated as you are now. I've started to slip a little though as I've lost 2 stone, Christmas has just happened and I'm not feeling as motivated as I was before (sound familiar?

) Anyway, it's great that you're feeling motivated and I think you've rejoined at a really good time since Christmas has just gone and it should be fairly easy to stick to plan.
As you probably know, writing everything you eat and drink down for the first few weeks is a great way to stay on track. I just bought myself a weigh loss tracking journal (not the SW one, just a cheap one from eBay) and I'm planning on going back to basics and writing everything down for a while to try to get back on track. There are some other ladies in my group that have done the same thing, which seems to have worked for them.
Other than that, I find that this forum is a great way to help me stay on track as there's always loads of support here and I sometimes just sit and browse through the success stories to remind myself that it is possible! Maybe take a look at the challenges section as there are some fun ways in there to help keep you motivated and accountable.
Finally, one thing I do all the time is fancy something really naughty to eat but when that happens I go to the SW website or just into Google and look for a SW friendly version of whatever it is I want. I haven't had a case yet where the meal I wanted didn't have a healthy alternative so I've gone out, got the ingredients and made it myself. There's an excellent recipe section on here too so you're bound to find something in there that will help
Best of luck to you! I'm looking forward to seeing how you get on
