Jennifer -

You have the weight loss benefits of youth, but at the same time, since you aren't too far above your ideal weight it will be more difficult to lose quickly. Exercise would definitely go a long way towards speeding that up, and yes, 30 minutes a day is enough. I don't know if you're exercising already, but if you presently have an aerobic base you might consider doing something like High Intensity Interval Training (HIIT). I believe that a normal session of that tends to be 30 minutes or less anyway, with health and performance benefits equaling or exceeding those of traditional, long cardio. Weight training wouldn't hurt either.