I am the same exact way! I'll be thinking positive about eating healthy and then after a few days, I'll put all of that down the drain. Your best bet is to talk to your parents about the food they buy for the family. I talked to my mom about it and now she rarely buys junk food, except on special occasions. Keep saying to yourself in your mind when you're looking for something to eat; do I want to fit into those or not? It might help. Good luck!