I have decided to run a marathon.

I’m not sure quite how I came to this decision. It’s not as if I wake up every morning with a huge desire to run 26.2 miles. I guess it came down to the never-ending siren song of challenge that I find so difficult to ignore: the joy of pushing the limits of what you believe yourself to be capable of accomplishing.

This October I will be running farther than I ever have before — probably the farthest I will ever run in my life — through the streets of Baltimore.

Making the decision to train for a marathon has certainly altered my life. Running a marathon is, after all, much more than just a one-day, 26.2-mile race — it means months of preparation. Four mornings a week, I get up at 6 a.m. to log my miles. Sometimes, waking up and lacing those sneakers is easy, and running feels fantastic: The air flows easily in and out of my lungs, and my legs feel powerful and strong. Even before the endorphins kick in, I get a rush from my own feeling of capability.

Other days, it isn’t easy at all — it’s all I can do to get up, put my shoes on and drag myself along my usual running route.

Easy or hard, when I finish my run I have a resonating (if sore) sense of self-satisfaction from the top of my rain-soaked head right down to my aching calves. By the time October comes around, I will have run almost 500 miles in preparation for this event. When not running, I am cross-training, swimming laps in the pool to keep my nonrunning muscles strong, too.

One of the first changes I’ve noticed from training is that I’m hungry.

“I don’t know if my food budget can keep up with my caloric needs right now,” I joked as I poured myself a glass of orange juice. Let me tell you, a 10-mile run will really make you crave that extra egg on toast.

I have always been active, if not athletic, but this is something different. “Marathon” is that word people use when they want to describe anything long and hard. Just on a mental level, I work hard to convince myself that I can do this.

But I will not be training for this marathon alone. Nor am I running wholly for myself. I’m running this marathon as part of Team in Training, a group of individuals running for the Leukemia and Lymphoma Society.

Every Saturday morning, we get together and train, sharing tips on everything from how to drink water while running (most suggest at least slowing to a walk if you want the water in your mouth and not on your shirt) to what kinds of running sneakers to buy. Each of us is committed to running this marathon in the name of blood cancer patients — and to raising $1,600 apiece to benefit the Leukemia and Lymphoma Society.

“I’m running this marathon because of my mother,” one woman said. “She’s a cancer survivor.”

“I’m running because I am a cancer survivor,” said another man. “I’ve been in remission for two years now. I’m not sure what feels better … being able to run or being able to help other people who are in the same position I was when I was diagnosed.”

We e-mail each other encouragement during the week and share photos of our “honorary teammates,” two local youths who are fighting blood cancer. Matthew, 4, has been diagnosed with B-cell acute lymphocytic leukemia, or A.L.L. Though he cannot leave the house while undergoing chemotherapy, his older brothers keep him entertained. Justin, our second honorary teammate, was diagnosed when he was 6. He just celebrated his sixth year off chemotherapy treatments.

I run for the challenge and for the mental and physical strength that running gives me. But I also run because training with the Leukemia and Lymphoma Society feels right to me. Most of us have been affected in some way by cancer. Alongside my teammates, I find the inspiration to push myself athletically in ways I never have before.

I don’t know if I would be able to run a marathon on my own. I know that no one person could raise the money needed for cure research and cancer treatments on their own, and I know that no one should have to fight blood cancer alone. The way I look at it, especially on those days when lacing up those sneakers feels like a Herculean feat, we are all in this together now — that is how, one way or another, we will be crossing the finish line.

Meg’s Web site is http://pages.teamintraining.org/md/balt09/madamsjsjo

Meg Adams, who grew up in Holden and graduated from John Bapst Memorial High School in Bangor and Vassar College in New York, shares her experiences with readers each Friday. E-mail her at madams@bangordailynews.net.