Lisette Ross is on a mission. And luckily, there's an app for it.

The 5-foot-tall mother of two has lost 40 pounds since April, when she decided, "I can't do this anymore, I feel terrible."  Ross was her heaviest after her second pregnancy.

"By the time I delivered my daughter, I was 263. I managed to maintain a good 252 to 255."  Her goal is 125 pounds, Lissete's weight when she got married. She wants to literally lose half her body weight without resorting to surgery. 

"I've heard too many people with complications," she said. "I've heard too many people who managed to gain the weight back."

So to help her keep track, she uses her iPhone and an app called "Lose It."  

"That kind of told me, remember if you want to lose this many pounds a week you have to eat this many calories a day. She enters what she eats, and the app does the math.  

Ross's game plan is simple, but not easy. Her husband moved their treadmill to the living room, making it a focal point. After being sedentary for more than seven years, she now walks four miles every day and carefully watches what she eats.

"Our portions are too big. You need to reduce your portions and factor how many calories you're taking in." 

Ross now looks forward to stepping on the scale to keep track of her progress. The app on Ross's phone says she'll reach her goal weight by July 2011. From now until then, she'll walk the distance between Miami and New York.