1. make a meal plan for the week
2. write down everything you eat and all the exercise you do
3. do something active every day
4. reward yourself
Don't be afraid to use each and every day, each and every meal, as a time to get back on track. If you blew it at lunch, eat a lighter dinner. If you didn't eat breakfast, have a filling snack as soon as possible. Didn't make the gym today? What's stopping you from walking or doing chores?