Edge of the seat
Keep your spine straight and sit on a chair. Use both hands to hold the edge of the seat and engage your core. Use the muscles of your stomach to put your feet up at least two to four inches off the floor, as you point your toes forward. Hold for three to five seconds then lower your feet down. Do eight to 12 reps.
Stand with your feet a little more than hip-width apart as you begin this exercise. Take a dumbbell and hold it at chest level. Next, lower yourself as you bend your knees. Use your core strength to lower your butt. Make sure that your elbows are inside your knees and keep going low as much as you can. You must make your abdominal muscles work contract them. Do at least 10 -15 reps.