Start saying "No" to empty calories... like soda
Are you addicted to soda? I'm not, but I know many people who are. I know one person who can only get through work if she has a 2-liter bottle of cola on her desk. That's a lot of empty calories.
My advice...take it slow. If you're addicted to "x" number of sodas a day, try to reduce that number slowly. Especially, if they are caffeinated sodas. Caffeine and sugar are both addicting, and stopping cold turkey will most likely result in headaches and other unpleasant symptoms. But gradually reducing your intake, will increase your chances of success.
If you only drink soda occasionally, just stop, and say no to soda forever.
I read somewhere that a person who stops drinking soda, can lose up to ten pounds over the course of year, without dieting. If you're a soda drinker, give it a try and let me know how you make out.