While my kids and I were out for a walk recently, my daughter asked me a great question: “Why do people litter?” As always, she got more of an answer than she bargained for, but the gist of my response was this: In this throw-it-away society, some people don't respect the environment — either by choice or because they weren't taught to consider the impact of their actions. That's what makes Earth Day so great.

A wonderful occasion to promote environmental awareness, Earth Day first took place on April 22, 1970, with 20 million people rallying to take part. This year, April 22 marks the 38th iteration of Earth Day, with an impressive 1 billion people expected to participate in more than 170 countries.

Although we do have much to celebrate, I can't help thinking that since Earth Day's inception the state of our planet has been like a glass that is both half full and half empty. On the one hand, we could say that we've come a long way with recycling programs, the reduction of pesticide use, growth of the organic foods and textiles markets, and new developments in alternative energy. On the other hand, we're desperately rushing to turn back the clock on climate change, pollution, and our overuse of water and energy resources.

But rather than proclaiming doom, this is all the more reason to get involved. Take part in an Earth Day celebration near you, and then continue to learn about and get involved in environmental issues with the help of events such as the Green Festivals (greenfestivals.org), which take place across the country throughout the year. At the same time, bring the message closer to home with simple steps like those found in “Earth Day and Beyond” and “Detox Your Home.” Of course, if there are children in your life (whether they are your own, nieces, nephews, friends' or neighbors' kids), it's never too late to begin to nurture an eco-conscience. As Bevin Wallace writes in “Kid Planet,” “By helping kids experience the natural world, parents can encourage them to become future stewards of the Earth.” It's certain we'll need these stewards to help raise the levels in our half-empty glass.