I know what you mean. I have some busy days in my week and some non-days. The busy days are SO much easier!
But pollyy's right - take up a hobby of some sort. It'll give you some focus and make it much easier. Doesn't matter what, it could be drawing or knitting or sewing or reading or going for long walks, or whatever! Use your imagination...
A good thing to do is to write down a list of the reasons you're starting this diet. Also write down a list of goals - make them quite small, because then it's easier to reach them. Once you reach your goal, treat yourself in a non-food way, like a nice hot bath or whatever.