It's the day after Cyber Monday but the deals are still going strong at GNC . Today only, get 20% off just about everything with coupon code DAYAFTER in your cart. Grab the products you need to keep yourself healthy this holiday season. Or, snag some stocking stuffers for the fitness buff in your life. Thousands of items are on sale! Plus, get $1.99 flat rate shipping on any order. This one's too good to overlook. Check it out before it expires tonight, 12/03/2013.