Pedometers get right in your face and make you own up to your slothfulness. You're sedentary if you don't hit 3,000 to 4,000 steps per day; some move at a ghastly 700. Ideally, adults should exceed 10,000 steps each and every day, a feat typically achieved only by children and adolescents. The over-50 crowd hovers around 6,000 to 8,500. But here's the number to remember: A half-hour brisk walk counts for about 3,000 to 4,000 steps, and for most adults, that brings their activity levels to the threshold that starts signaling those health-promoting genes to start pumping.

Sure, there is personal variability. Some people are genetically more susceptible to certain chronic diseases than others, and the exercise levels that yield health benefits for individuals can differ. But whatever hand the gene gods have dealt us, the need for everyday physical activity is coded into our DNA. You simply can't walk away from it.