You don't HAVE to give up the diet soda ... completely. Just whatever diet soda you're drinking, drink
less. Again, I think this depends a lot on the individual.
For me, this wasn't a diet issue as much as a dental issue. Dentist really gave me grief last fall about lack of tooth enamel on my front teeth -- attributed almost directly to soda consumption. (And, this is with using a straw 80 percent of the time.)
I was with Diet Dr Pepper like Jenn was with her Mountain Dews.

Five or six a day was
normal. So, for my New Year's resolution, I vowed to fix it. I actually started before the end of the year and by New Year's, I was drinking three or less a day. Now, I average 1 a day, occasionally drinking 2. The rest of the time I drink water. Man, was that hard. Took at least a month before I was pretty comfortable with it. Now I
savor my sodas, much the way I would any other treat!
It really is an addiction. Maybe not as strong of one as nicotine or alcohol, but caffeine is addictive. I knew better -- for me anyway -- than to go cold turkey. The headaches it brought on weren't worth it. Easing away from it worked much better.