How can I do it again?

In the past, I had a few years when I was able to just have water or tea at the party and enjoy socializing while everyone was stuffing their face with food. I used to be so fine with that. It’s different now. I began overeating and am having a hard time not stuffing my face when others are. I do not remember how I did it and what thoughts I was thinking when I was able not to eat while others around me were eating. I want to live that life again.