Photo: lanier67 via FlickrWith the arrival of this year's 40th anniversary of Earth Day, it is encouraging to see more and more people, young and old, buying into a meaningful environmental ethic in their personal lives despite daunting environmental challenges. By carrying reusable grocery bags, taking public transit and recycling, to name just a few examples, we are all becoming increasingly aware of the need to be environmentally responsible. If you're a smoker, there's another very important step that would be a "twofer" win for your health and for the natural world: Quit for good! Surprisingly, many of us don't …