Controlling Cravings

How can I control my cravings? I'm trying to eat better and make healthier choices, but I'm always craving what I shouldn't eat. I tried chewing gum whenever I felt hungry, but it only helps for so long. My goal from eating healthier is to finally have a flat stomach and to learn to take better care of my body by eating nourishing food. I used to hate sugary food because a couple of years back, I actually disciplined myself into eating right and exercising and avoiding sugar as much as I could eventually made it something I was okay going without (unless it was a birthday or special occasion). I'm also slipping back into not drinking as much water as I should. I used to never drink regular soda unless we went to a nice sit-down restaurant and I would allow myself to indulge.