Here’s why: It can actually alter your genetics, and lower the activity in the ones that influence body weight. Harvard researchers studied 12,000 people – and measured how many fat genes each person had and how much they exercised. The ones who walked briskly for an hour a day cut the effect of their weight-promoting genes in half! But the opposite is also true. Hours spent sitting can make those fat genes more active! So we DO have some control over our genetics. The trick is to make it work in your favor by walking an hour a day.