I'm Dr. John Izzo. I'm an author, a business leader and I am a Baby Boomer, part of that generation aged about 47 - 64 years old who when we were young believed that we would make the world a better place. During my first month studying journalism at Hofstra University in September of 1975, I wrote an opinion piece in the university newspaper called "Generation gap" pondering what my generation would be known for. In it, I suggested that if my generation were not careful we would wind up being known as the generation that focused on material things while all the big problems facing the world got worse. Almost 40 years later I'm musing -- what will my generation actually be remembered for? What will our legacy be?

Let's first admit that we may be living in one of the most critical windows of human history in a time when decisions we make in the next 10 - 20 years will mean that my generation especially will either be one of the most cursed generations in human history or one of the most praised. Let's also admit the current trajectory is not a pretty picture for the boomer legacy.

The arctic ice is melting, the climate is changing fast, we're extinguishing species a thousand times faster than the historic average, the coral reefs are dying, and there are dead zones in the ocean. Half the world lives in poverty and this growing gap between haves and have nots is causing unrest and tension all over the world. One in every six human beings lives on less than a dollar a day, and one every two or almost 2 billion of us live on less than a dollar a day with no access to sanitation or electricity.

And all of this is about to get a lot worse because of a demographic time bomb about to hit us. You see 52 per cent of earth's population or over 3.5 billion people are under the age of 30 with the vast majority of them in developing countries -- places like China and India -- people who rightly want to drive cars, build houses and live the life we have lived in the developed world for decades. They will have their own children which is why by mid-century there could be 10 billion of us -- 54 per cent more people than live on earth now! Tensions are rising all over the world and nuclear proliferation is becoming an uncontainable problem. Get the picture? Half the world already lives in poverty, the population will grow by 50 per cent, one to two billion will try to move into the middle class making most every environmental problem much worse, unless we step up and decide to act.

So the important question is: Which generation is most responsible and most able to do something about this problem? When asked in a recent survey from Free the Children, 80 per cent of teenagers said young people are going to change the world and only 1 in 5 said that people my age are the most responsible and the most able to solve this problem. In that same survey when they asked people my age, 45 - 65, which generation is the most responsible and most able to fix this problem, only 15 per cent of us said us. A staggering 85 per cent of us said "someone else" needs to fix the problem. I find this incredulous! How can my generation (the boomers of the developed world) the generation that holds 85 per cent of the wealth, runs almost every major corporation, and has the most political muscle in every developed democracy in the world possibly think someone else is more responsible than us? How can the generation that is going to be the healthiest, longest lived, most educated and wealthiest older generation in human history actually believe that we are not the ones?

So I started thinking about who could be our mentors in stepping up? And I thought of an unlikely source -- our parents. They are the generation that lived through the great depression and not only endured it but built a giant safety net in the developed world that pretty much kept from having another depression a couple of years ago. This is the generation that stepped up when they were only in their late teens and early twenties as totalitarianism started to spread all over the world in Asia and Europe. By the millions they took the first foreign trip of their life leaving their innocence, youth and often their blood and lives on foreign shores. And back home men and women brought war bonds and rationed gas all for the most part to help people they would never meet. That's why Tom Brokaw named them "the greatest generation."

It made me wonder what my generation would be named and I think they're going to call us the Luckiest Generation. They're going to say they we're the generation that lived after the really bad stuff happened, and before the next really bad stuff happened. We were the luckiest generation in the developed world in human history living in the most stable, peaceful, wealthiest societies of human history. And if we are not careful they will call us the "Lucky Suckers" who lived the high life and pretty much sucked the air out of the room before we left leaving our kids and grand kids with huge problems to solve.

This isn't the legacy I want to leave, so I think now is the moment for my generation to step up and decide to use our education, our wealth, our time and our encore careers to tackle the biggest problems that humanity has ever faced. I believe we need a veritable Gray Corps -- an entire generation of people my age that decide to use our encore careers to create sustainable technologies, to use our time and our political muscle to make sure these conversations become central to our political and corporate discourse, to do the equivalent of sacrificing like our parents did for something greater than ourselves. There is a reason so little is being done to tackle climate change, poverty and eco degeneration and it's because boomers are still mostly focused on ourselves and our material happiness.

Yet there are signs of hope. A recent survey in the USA found that the 45 - 64 year olds were most likely to see climate change as an issue that must be solved and baby boomer Bill Gates is not only giving away most of his own wealth to solve the big issues of our age but has challenged other billionaires to make the same commitment which forty have done so far. What we need are boomers of all strata to start using our wealth, our time and our political muscle to decide to create a more sustainable future to hand off.

My stepfather was one of those people in the greatest generation. When he was only 20 years old he volunteered to take the only foreign trip he would ever take and stormed the beaches of Normandy. For several years he fought across toward Berlin until his second injury sent him home. Although he never talked much about it, once a week or every other week he would don that old army jacket and go down to the VFW hall on Friday night and hang out with those old veterans and I never knew why. I think I know now. I think it was because all of his life until he died 10 years ago he carried within him this pride that when he and his generation had been called, they stepped up. And I don't know about you but when I'm 80 years old I don't want to be sitting and apologizing for what my generation did. I don't want to be apologizing for the fact that all the time that we were in power we thought somebody else should solve this problem when everybody knew it was coming and we did nothing about it.

This is THE moment for my generation. We will either be known as the luckiest generation or we will be known as the wisest generation who chose, before they died, to solve the biggest problems that humanity ever faced. We will either be known as a generation who took our oldest years to solve the problem or we'll be known as a generation forever as one big apology in human history.

So here is my advice. If you're not a baby boomer I want you to send this blog and video below to every single baby boomer you know. I want you to say we can't have you check out! We need you! Sign up! This is your problem. Help us fix it. And if you're a baby boomer I have one simple thing to say to you...put away the cruise tickets, there's work to be done.

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• See A Doctor First

  This may seem like a no-brainer, but if you've been idle for a while, it's important to see a doctor before getting active again, says Dr. Alexis Colvin, an orthopedic surgeon at The Mount Sinai Medical Center in New York City. You want to make sure you don't have any pre-existing conditions, such as heart disease, that might present a problem when you start up your new exercise regimen.

• Start Slowly!

  Getting active too quickly, often with incorrect form, is one of the primary reasons people over 50 find themselves in her office, Colvin says. It's important to slowly build a base level of strength, flexibility and fitness before pushing yourself to, say, sign up for that marathon.

• Consider Seeking Professional Help

  It's always helpful to have a little direction and support in starting something new. Colvin suggests getting started with a personal trainer or physical therapist to tailor an exercise program to your goals.

• Get In A 'Pain-Free Zone Of Activity'

  Low-impact activities, such as swimming or using the elliptical, are all good for people who have joint pain, says Dr. Colvin. If it hurts, don't push it!

• Think Beyond Cardio

  An active lifestyle isn't limited to throwing on some running shoes and hitting the pavement. Dr. Colvin suggests yoga and pilates, which can help with strength and flexibility even if they don't give you the same cardiovascular workout you might get from the treadmill.

• Think Outside The Box...Or, Should We Say, The Gym

  Colvin also points to the many home exercise videos available, which can be a great alternative for those who would prefer to exercise from the comfort of their living rooms. The one drawback, she says, is potential for injury from using incorrect form, "since there's no one watching you."

• Consider Cross-Training

  Mix up your routine and <a href="http://sportsmedicine.about.com/od/tipsandtricks/a/Cross_Training.htm" target="_hplink">consider cross-training</a> (adding swimming and biking to a running program) to prevent boredom, avoid repetitive injuries and improve your overall condition. Exercise with friends to add social benefits to the physical and mental advantages of your workout. Recognize your limits, adjust accordingly and enjoy the quality-of-life benefits of an active lifestyle for many years to come.