I WOULD LIKE TO KNOW IF USING A SIX INCH IS JUST AS GOOD AS A EIGHT INCH STEP. I HAVE TRIED A EIGHT INCH STEP BUT IT HURTS MY BACK. AM I STILL DOING ANY GOOD AS FAR AS CARDIO GOES? I KNOW I AM NOT ADVANCED LEVEL. DO YOU GIRLS EVER GET OUT OF BREATH? DOYOU EVER HAVE TO STOP AND TAKE A BREATHER?YOU GIRLS SEEMS SO STRONG.