Just in time for Earth Day, the EPA has come clean: Global warming is bad for health. On April 17, 2009, the EPA found that "greenhouse gases in the atmosphere endanger the public health and welfare of current and future generations." Turns out that heat waves, wildfires, flooding, rising sea levels and more intense storms are bad for people's wellbeing, too. Who knew?

So reducing your carbon footprint is a healthy act. More directly, taking care of your health can be good for the planet. Eat less beef, more beans? Less risk of cancer and heart disease, less carbon produced in the agricultural process. Walk or bicycle to work instead of driving? You'll be fitter and spew less carbon. You can even save money.

Nature may help heal the mind, too. Spend an hour walking in the woods and you begin to shed the ultrastimulating nature of modern life that makes attention-deficit disorder a social malady as well as an individual diagnosis. Contact with nature can decrease mental fatigue and accidents, and enhance mood and concentration.