How to lose fifteen pounds quickly?

Diet and do cardio exercises (ex. run 30-45 mins a day). As you get more comfortable with exercising, try increasing the distance. You could also try some ab workouts (ex. crunches, leg lifts, or bicycle crunches), and if you are truly serious about it try doing some weights, but like 2-5 pounds, don't do heavy weights, too much muscle looks ugly on girls.