Believe it or not, form matters when you're walking, too, explains Natalie Johnson , a NASM-certified trainer and running coach. Concentrate on keeping good posture, maintaining arm mechanics, taking shorter steps, and walking through your big toe, Johnson says. "You may feel like you want a bum bag and visor pumping those arms like you would if you were running, but believe me it sets you up for better running mechanics," she says. Paying attention to your form also keeps you from zoning out: "You want to allow yourself to [walk] without losing sight of the purpose of your run," Fitzgerald says.