First, grab an exercise ball. Using an exercise ball for stomach toning gives you stronger muscles than if you did the exercises on the floor. Plus, you get bonus benefits, like better balance.
Sit on the exercise ball, feet flat on the floor, knees hip-width apart and bent at a 90-degree angle. Place your hands behind your head, elbows pointed out, and slowly roll back until your mid to lower back rests on the ball. Pull your ribs toward your pelvis to raise your upper back three to four inches off the ball. Hold for a second and then return your shoulders to the ball. Repeat 10 times.
For Back Building: Supine Bridge
Keep that exercise ball around for this one. Sit on the ball with your knees hip-width apart and bent at 90 degrees, feet flat on the floor. Roll, so that your shoulder blades are resting on the ball and your torso is suspended above -- and parallel to -- the floor. Like a bridge. Tilt your pelvis, so that your bottom dips toward the floor, then bring it back to original parallel position. Relax and repeat 10 times.
For Sleeker Sides: Side-Lying Leg Lift
Put your exercise ball aside; you won't need it for this one. Lie on the floor, on your right side, with your right arm extended in front of you for balance and support. Keep your torso straight, aligning your shoulders and hips so that they form a straight line with your ears. You can bend your right knee slightly for balance. Keep your left leg straight and slowly lift it upward eight to 10 inches. Your left heel, knee, hip, shoulder, and ear should remain in a straight line. Lower your left leg slowly. Repeat 10 times and switch sides.