Flatter Belly - Upper Lower Daily Workout: This is a basic workout that you can do every day to help flatten your belly. It is a great workout for people of all ages and fitness levels. 1. Warm up by doing some light cardio or stretching. 2. Do the following exercises one after the other, making sure to keep your core engaged the entire time. a. Double Crunch: Lie on your back with your legs bent, and your hands placed behind your head. Crunch your torso up towards your chest, and then lowe