When I need to get back on the wagon I go back and do research, try to remember what you did like and make a plan! Plan all your food for the whole week on Sunday (that is when I have time), and make sure to plan some activities for the time of the day you know you will be looking for a snack for no good reason!
Once the research and plan is done take it day by day. If I get overly consumed with having to deal with my eating plan all week I go crazy! So I just try to stick to the present even meal by meal....