Try Hiking with a Backpack (500 calories)
Working out with weights increases muscle mass and boosts metabolism, helping burn calories throughout the day. Weight-bearing exercises like squats and lunges can also increase bone density, helping forestall conditions like osteoporosis. Hiking with a pack (and a pair of poles) does all that and provides an intense cardio workout. And have we mentioned the views? There's no contest: On weekends, grab your pack (even if it's filled with hardcover Jane Austen novels) and head for the hills.