Exercise can help. Try to walk 30 minutes most days of the week and see if that gets your weight loss rolling again. If you are already walking, consider making an appointment with a personal trainer to help begin a gentle strength-training program. If both of these things are in place, then it’s time to review your calorie intake. Even if you are following the South Beach Diet faithfully, if you are eating too many calories, even if they are the right calories, you won’t lose weight.