Cardio (such as running) has always been one of the best weight loss exercises. Runners have great abs. If you plan to invest in running, get good shoes and compression shorts.

But diet definitely has a big part too. Take out all the soda, replace with water and tea (actual tea, not brisk). Instead of chips, do baby carrots with a small dip of ranch (not too much or else you're eating fat and not veggies). Theres plenty of things you can do. Learning to cook is really fun and awesome for eating healthier as well. BudgetBytes has some great, healthy, cheap recipes; her dishes appeal to even picky eaters.