Crunch this

If you are bored with crunches, and you want to shake up the abs, give this exercise a try. It's called an exercise ball pull-in; so, obviously you'll need an exercise ball to do it.

Here's the set up: get into push up position with the front of your legs and feet resting on an exercise ball. Keep your body parallel with the floor. Your abs should be nice and tight so your back doesn't sway. Roll the ball toward your upper body by bending your knees and crunching your abs. Keep your midsection stable. Pause for a count before rolling the ball back to the start position.