The vast majority of people who run marathons don't do it for the money or the chance to represent their country at the Olympics. They do it to push their limits, to try to shove back the hands of time or because they love picking at the blisters on their feet.

Sometimes they do it because others can't or to raise awareness and money for a pet cause.

I've seen firefighters and soldiers in full gear running marathons. Once in Boston, a guy glided past me wearing a t-shirt that read "Through God all things are possible." He wasn't gliding when I slipped past him at mile 17.

This weekend in New York City, 47-year-old Andre Ditto will be running one of the biggest marathons in the United States carrying a backpack stuffed with almost 15 kilograms college textbooks. He wants to raise awareness about the high cost of textbooks.

Textbooks can cost students $1,000 a year. And the price of textbooks has been rising at twice the rate of inflation.

Among the titles Ditto will be hauling is "Art History" by Marilyn Stokstad which the New York Times labeled as the heaviest university textbook in the world. At more than 1,200 pages, it weighs in at almost five kilograms.

Now, Ditto's not doing this for nothing. He's convinced CafeScribe, a website that promotes electronic textbooks, to pick up the cost of his daughter's university books for a year.

Still, carrying that much weight for the marathon distance has got to lead to a lot of chafing.

But Ditto should be up to it. He's a personal trainer who lost more than 40 kilograms 10 years ago through exercise — mainly running — and diet.

He's not looking to raise money, but hundreds of thousands of runners and walkers do.

Figures released earlier this week show that south of the border, road runners and walkers raised $714 million US for charities in 2006. That's up nine per cent from the year before.

Fundraising is a big part of these events in Canada as well. For instance, the 60-kilometre Weekend to End Breast Cancer walk last September raised an estimated $17.3 million.

In most races, a portion of a runner — or walker's — entry fee goes to a charity of choice.

Many of those charities are health-related and touch us all. So think of that, as winter's about to force recreational runners off the paths and back onto the streets. Steer clear if you see us on the roads. We're doing our bit for the health-care system.