Soda is my cigarette like vice. I've quit hundreds of times in my life. Sometimes just doing it by willpower. Sometimes because I get tired of my current favorite soda flavor. Then somebody tempts me with their favorite, and I get hooked. Or I am eating out and the water tastes like butt, and I don't really like coffee, tea or alcohol, so I get a soda. And that is all it takes. Suddenly I'm drinking it again.
Like I said, I have quit soda flavors. Used to love Dr. Pepper. Now I wouldn't drink it if I was dying in the desert. Same with Coke and Pepsi.
And diet soda tastes awful, so what is the point? Water is way better than diet soda.