'Tis the season to go shopping. Yes, those furious lines of holiday shoppers might as well be a bunch of health nuts. An hour and a half of shopping burns 242 calories. But if you're speed-walking (4 miles per hour) around the mall, tack on an extra 526 calories burned. All of which equals a grand total of 769 calories burned, more than the 715 burned in 90 minutes of low-impact step aerobics.