Instead of: A bench press or ab bench
Use: A blow-up exercise ball ($20 for Gaiam Total Body Balance Ball Kit, which comes with the blow-up ball and the pump at amazon.com).
Size: Deflates to a flat ball that can be scrunched to the size of a small box.
Expert says: "Exercise balls are awesome for abdominal workouts, but they are also a good way to change your base of support," Savion said. For example, instead of doing a chest press on a bench, you can lie on an exercise ball. You can use this for everything from assisting with a squat to strengthening your inner core by doing crunches on the ball, she said.