There's only two things you can do:

1.  Eat smaller portions, and
2.  Find an exercise you enjoy so you stick with it.

This isn't a quick fix, just so you know!  This has got to be a lifestyle change.

In my opinion, no fat/carbs/sodium equals no flavor.  You can eat the foods you love so long as you eat small portions of them.  (A slighly heaping serving spoon of mashed potatoes measures 1/2 cup.)  Any and all diets will fail if you don't practice portion control.  Eat small meals every few hours.  Eat slowly--use a smaller plate and eat your dinner with a dessert fork.  (Smaller mouthfuls make you slow down, so you know when you've had enough.) 

Exercise wise, find something you love doing besides exercising your thumb on the remote control.  What do you like to do to move around?  Do you like to dance?  Buy a pair of rollerskates and skate around the local park.  Ride a bicycle.  Take up a sport.  Whatever you can do to move your body--we weren't made to just sit around on our rear ends!