Michelle Obama's longtime trainer is breaking his silence, spilling the workout secrets that keep the First Lady fit for her favorite sleeveless outfits. "She's truly committed herself to the importance of health and fitness," Cornell McClellan tells Women's Health magazine. McClellan, who began training Obama in 1997, said her sculpted arms are mostly the result of tricep pushdowns and hammer curls. The trainer, who owns the Naturally Fit fitness center in Chicago, reveals the First Lady usually does an intense calorie-burning cardio workout. Once she gets the blood flowing and the muscles pumping, she tops it off with "arm-shaping supersets"...