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Building up your summer beach body? Take a cue from Julia Roberts’s trainer and pick up a pair of dumbbells. “People are so focused on cardio that when they can’t afford a gym membership, workouts go by the wayside,” says Roberts’s trainer Kathy Kaehler told InStyle. “Five-pound dumbbell weights allow you to do circuit and strength workouts, which keep your heart rate up, increase your metabolism and help you tone.” Pick up your own for $13 at amazon.com, and get more of Kaehler’s workout tips by following her Twitter, @kathykaehler.

Plus, see more star-inspired workouts!

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