10 exercises that will help you achieve a flat & toned belly. (From the app 'Ab Workout') by Amy Lane 10 exercises that will help you achieve a flat & toned belly. (From the app 'Ab Workout')Do anywhere from 10-30 crunches for each exercise, and 30-60 seconds for the plank. Starting out at a low number and progressing to a higher number is the goal! Be consistent and don't forget to eat healthy as well!