Since about this time last year, I have been working toward a six-pack. (or at least minor ab definition) It's definitely a two-part process though.
Part one is the working out aspect. Following workout plans such as Insanity or the Blogilates calendars help since it eliminates the need for you to make up the routine yourself. However, unless you're doing it with someone else, it's hard to stay motivated and continue to do the workouts each day! Plus, those tend to be 1 hour+ which can be hard to fit into your schedule and can be a lot on top of all the dance classes I take.
Since I have a lot of time at home and tend to listen to music a lot, I make a lot of playlists. So, I pick one or two songs and choreograph a workout to the entire song. Then, I include it any playlists I'm listening to that month and play the playlist on shuffle. Whenever it comes up, it doesn't matter what I'm doing, I get up and go through the workout. It offers a nice break from what I'm doing and makes it so I don't have to do a crazy long workout all at once.
The second part involves the diet. Most diets aren't exactly healthy and you should always eat when you're hungry, but it is important to not eat out of boredom. What you eat is important too. Instead of getting a burger, fries, and coke for dinner, go for a chicken sandwhich, side salad, and water. It's also important to eat when you're slightly to moderately hungry. By the time you're "starving" you're more likely to binge when you do eat.
Do you work out daily? How do you stay motivated?