That's 20 to 25 minutes of walking, covers about a mile, and will burn about 100 calories a day—enough, Hill said, to prevent gradual weight gain in most people.
"It doesn't matter how you get there," Hill said. "It can be all at once or spread out. Once you do get there, do more."
Some of Hill's suggestions for sneaking in extra steps: When you step outside to get your mail, walk around the block before going back inside; do some errands on foot; at work, park at the far end of the office lot and use a distant rest room.