Stephen trains Sarah with Nelly's favorite celebrity ab workout, the weighted crunch. Find more fitness videos at diet.com or own this video for just $0.75! Also check out our Britney Spears ab routine at www.youtube.com Check Out Diet.com Video! Diet.com: www.diet.com Subscribe to Our YouTube Channel - www.youtube.com Go behind the scenes w/ Sarah's Blog- www.diet.com Twitter twitter.com Facebook: www.new.facebook.com iTunes: tinyurl.com Sarah's Fitness Blog - www.examiner.com...