AFTER crossing the finish line of the 2013 Boston Marathon, I leaned against a school bus, exhausted but elated, and pulled track pants over my shivering body.

To train for the race I ran 442 miles over 12 weeks, but none of that prepared me for what happened next.

A boom echoed throughout downtown. Another one followed. Looking down Boylston Street, I saw a plume of smoke rising above the buildings.

One thing you learn from running marathons is that no matter how good or bad you feel, that will change.

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At mile 21, the crest of the famed Heartbreak Hill, Boston College students had erected a giant inflatable arch that declared, “The heartbreak is over.”

Now, past the finish line of the 117th Boston Marathon, I sensed the heartbreak was only beginning.

In 2004, when I trained for my first marathon, I did it merely to say I had done one. My world felt chaotic; I didn’t know where I should live or what kind of work I should do, but running restored order. With a training plan, I had something to accomplish every day for the next six months.

That fall I ran my first marathon, Portland. On race day I realized that running isn’t really a solo sport. At times the breathing and footfalls of hundreds of runners were indistinguishable from my own. A marathon was something you had to do on your own, but we were all in it together.

Afterward, I was curious to see what it would take to run Boston, so I looked up the qualifying time for a woman my age: 3 hours 40 minutes, which seemed not just impossible but ridiculous. (The qualifying times have since gotten stricter.)

The Boston Marathon was the first race I ever saw live and in person. Late on Marathon Monday in 1996 I stood near the finish line and watched the stragglers come in. In the days leading up to the race, I had witnessed excitement of runners from all over the world coming into the city and how Bostonians embraced and celebrated them.

Boston was a dot on the far horizon, but I kept doing marathons anyway. When life got weird, running felt normal. Lost your job? Go for a run. Filed for unemployment? Run through that, too.

Dad in the hospital? There’s got to be a trail nearby.

After the bombs went off in Boston, I walked back to our hotel near Fenway Park. Dazed marathoners streamed along the sidewalks. The race had been called off before they could finish.

I fell in with a silver-haired veteran of the Boston Marathon, and we shook our heads in disbelief.

“The Boston Marathon?” I wondered aloud.

“Is nothing sacred?” he replied.

That night at a restaurant, I met a young woman who was half a mile from the finish line when she was forced to turn back. It was her first Boston Marathon. She couldn’t stop crying.

I asked one of her friends how I could help.

He said, half in jest, “Do you have an extra finisher’s medal?”

Before the bombs, sirens and heartbreak, I had glanced at my watch, which told me I would finish in 3 hours, 41 minutes and 27 seconds, which meant I had qualified for the 2014 Boston Marathon.

At the time it was cause for celebration, but in the days following the race I began to have doubts.

One thing you learn from running marathons is that no matter how good or bad you feel, that will change.

I heard some suggest that given the scope of tragedy in Boston, a marathon, with its focus on hours, minutes and seconds, is meaningless.

For many other runners and me, qualifying for Boston was a reason to press on, even when it looked as though we would never make it to the start.

Now that I’ve run it, I see the Boston Marathon not as a race, but as a state of mind — one that compels you to keep moving forward, even when there’s no longer a finish line.

Amy Roe is editor of Real Change, the Seattle nonprofit newspaper sold by homeless and poor people. She has been working on a book about the Boston Marathon.