What is it with fat?

I am struggling to understand my thought process. A year ago, I was headed down a physically self-destructive path, eating junk food every day, promising myself I'd quit. Last December, my father died of diabetes, misery & obesity. While I was never close to as fat as he was when he died, I was certainly headed in that direction. His death lit a bonfire under my ass, and I've been going to the gym faithfully ever since. I quickly lost a lot of weight, and have added a good amount of muscle. I'm stronger than I have ever been, and have turned my life around 180 degrees. So why is it that  nasty, fatty, fried chicken and nachos (separate dining events) are still foods I even consider eating (albeit rarely)? Nachos yesterday - a regrettable slip. But fried chicken 24 hours later? Yes, I beat my arms, back, chest and abs into submission today, but that would have happened without the poison I ingested. If I could vomit that fatty, nasty chicken out I would. Hooray for solid mental health! Lack of self discipline will get me nowhere....