Newer studies show when Americans get out of the car and walk a little instead, they're simultaneously fighting obesity and global warming.

If all Americans between the ages of 10 and 74 walked or biked a half hour daily versus hitting the gas pedal, one scientist estimated we'd:

• cut 64 million tons of carbon dioxide emissions.
• save 6.5 billion gallons of gas.
• shed more than 3 billion pounds.

Shifting away from heavy meat consumption toward a flexitarian diet would also positively impact the planet. The United Nations Food and Agriculture Organization reported in 2006 that 18 percent of the world's greenhouse gas emissions derive from the meat industry. Fruits, veggies and grains take significantly less energy to produce.

Perhaps the dual benefits of walking will motivate even more of us to step out of the car and onto the sidewalk.