I rationalize it's not that bad for me. There's no sugar or calories, and I've grown to like the taste of the aspartame/acesulfame potassium combo as much as real sugar. As far as I can tell drinking 1 liter of the stuff every day has not negatively impacted my health yet (although it may be doing so subclinically). It doesn't give me headaches or make me gain weight.
But I still want to quit because I feel like there's unexplored gains to be made by getting rid of the habit. I am wondering though, has anyone quit diet soda and felt much better? Has anyone quit and felt exactly the same? Has anyone been drinking diet soda for decades and feel like it hasn't harmed their health at all? I'm on the fence about this.