Start slow with the exercises. You don't have to keep up with the people on the DVD, just do your best. Adapt it to yourself. And walk! Just walking can do wonders. Try to eat real food, not out of bags, boxes, or cans. If you find yourself snacking out of a bag - stop, put some in a bowl (a small bowl), and put the bag away.

Good luck, skywalker. May the force be with you!