Griffe....maybe i'm giving the wrong advice here tho i'm sure somebody will come in and correct me if so...

...don't beat yourself up because you fell back...a new day is a new start. one day at a time, one hour at a time, one minute at a time...baby steps i call it. praise yourself for the length of time you do manage to achieve your goal, don't beat yourself up when you don't manage...the important thing is you WANT to achieve this and you're TRYING to achieve it...worth praising in my book.

....you can do it, hang in there, believe in yourself and don't give up!