"It takes a combination of good nutrition and spot-focused cardio-sculpting exercises to tone your triceps (the upper-back part of your arm)," says celebrity trainer David Kirsch, who has worked with stars like Anne Hathaway. See below for his favorite workout routine.WORKOUT 15 push-ups on a stability ball (place your hands shoulder-width apart on the ball, feet on the floor) 15 diamond push-ups (your index fingers and thumbs should touch to form a diamond). Tricep kickbacks with 3-5 pound weights (bend over at waist, keep bent arms tight at your sides, push your arm straight back and return). Rotate your palm up as you extend your tricep for added burn. Finish with a round of high-intensity cardio.