dont get so worked up over it, its not a big deal. have u got time to maybe start a sport? cause if you play a sport you naturally start to eat healthier because you wont be able to get through the day without getting the energy from healthy food.
also, its really mostly just habit. my parents dont buy junk food, its just not a polish custom, and ive never had the opportunity really to eat like that. so maybe when you go out shopping dont buy too many unhealthy snacks? i mean we do have chocolate and cookies at our house, but thats about it.
also, if u drink water, that usually fills you up, so always have water next to you.