Did you know that walking on sand burns almost twice as many calories as walking on a trail or road? If you have access to a beach, take your walks there as plodding across an uneven surface such as sand will make your muscles work harder, boosting your calorie burn. You can also try walking backward (look out for trees and people!), walking faster, and walking on trails not the treadmill at the gymâ€”all ways to get a better, more challenging workout. And not only will you use up more calories, your legs will become more defined and toned.