You've made a decision to get healthy. It will get easier. Ten months ago, the thought of tossing out my I Can't Believe It's Not Butter for real live OMG full fat/pure fat butter was one of the hardest things for me to do. Now: I Can't Believe I Used to Eat I Can't Believe It's Not Butter. IOW, it gets easier as it becomes a way of life.
One day you won't see popcorn as a treat, but as something not very wholesome. You might even be making your own jerky to eat at the movies. And please don't feel guilty - guilt over food will make you very unhappy.
"Right is right, even if no one is doing it; wrong is wrong, even if everyone is doing it." - St. Augustine