Marathons have become something other than athletic events in America. The psychology of stating "I ran the so and so marathon" is quite appealing so many attempt the challenge without doing the necessary prep to take on such a prolonged event. Don't get me wrong, it's fantastic that people want to enhance their fitness to take on an event like that. The truth is there is no quick path to training for such an event and many are not willing to do the adequate work necessary to properly prepare themselves. Injures are numerous and same names pop up consistently..... IT band syndrome, stress fractures, Achilles tendonitis, plantar fasciitis etc.
In many cases when people get injured they begin to rationalize their not suited for running distances and are turned off from the sport. In reality, the issues might be solved by training in a more systematic approach. When physical stress is applied to the human body it does a great job of adapting to the stress if it's in small doses. There's a very complex science to training and competing in long endurance events both physically and nutritionally and there's no shortcuts if one is to be successful and minimize the chance for injury.
Nothing in life worth doing is accomplished easily. It takes a lot of commitment over a long period to become successful at most everything from owning a business to competing in a marathon. And that's ok, because it's the journey that's makes us who we are.