"It's just a whole new layer of things we took for granted and can't now," Rood said. "It still plants that seed. It's still in the back of your mind."

'Try and stop this'

There are others who, though they didn't run in Boston, were motivated to take on a new challenge because of what happened there. Adrienne Dulaj, a local social worker, will run her first marathon Saturday.

"You want to run because there are other people who can't. If you can, you should," Dulaj said. "If there are people who … can't run anymore, I'm sure they would look at a healthy runner and say, 'You should run. You should run as long as you can.'"

Colleen Leonard, of Edgewater, signed up for the half marathon the day after the Boston bombings because she wanted to accomplish "the opposite of whatever the terrorists were trying to achieve."

She was reminded of Sept. 11, when she and her husband went to work in Washington, D.C., the following day.

"I really felt like, 'I'm going to work. Try and stop this. Try and stop what we have,'" Leonard said. "It was sort of laughable to me that going to work seemed courageous."

Dave Gell, director of communications for the Baltimore Running Festival, said organizers didn't survey entrants about whether the Boston Marathon had any effect on their decision to run. But he said spots in the relay and 5K sold out faster than ever. (The total field is capped at 27,000 runners, the same size as last year.)

"It's safe to say the local running community is undeterred by the tragedies that took place in Boston," Gell said in an email. "Terrorists could not have picked a more resilient group to mess with than marathoners and their families. We're back and we're as strong as ever."

'Something I hate to have to think about'

For Kevin Frick, the healing process continues. After Boston, he published 26 blog posts — one for each mile — to try and make sense of what he had been through and what running meant to him.

Frick finished the Boston Marathon on April 15 in three hours and 15 minutes, reaching the pinnacle of his running career at 1:21 p.m.

While on the way back to his hotel at 2:49 p.m., a pair of explosions shook the marathon's finish line, killing three and injuring more than 250 people. Later, Frick and a stunned nation learned 8-year-old Martin Richard was among the deceased.

That made Frick, a Baltimore resident and 17-year member of the Johns Hopkins faculty, think about his son of the same age. He thought about what might have happened if his family had decided to come watch the marathon in Boston. He thought about what would have happened if the explosives went off just a little earlier.

"Just because everything seems perfect doesn't mean the day is going to end that way," Frick said in a recent interview. "It's something I hate to have to think about, and yet, it's going to be that way."

In June, he reached the point where he no longer thought about it daily, and he no longer experiences the symptoms of post-traumatic stress disorder that worried his family those first few weeks.

Recently, though, he found himself becoming sentimental again. The shoes he wore at Boston were finally worn out. But unlike other pairs, he couldn't bring himself to get rid of them.

"I'm still not quite sure what I'm going to do with them," he said. "But I'm not going to just throw these out. That would not be the right thing to do."

Baltimore Sun reporter Yvonne Wenger contributed to this report.