Scott Rigsby travels the country giving motivational talks to corporations and at military bases. He gives a message most apt for Monday’s Boston Marathon. A Sandy Springs resident, Rigsby is the first double amputee to complete an Ironman triathlon.

“The main thing I tell them is today’s unthinkables can be tomorrow’s realities,” he said.

What might have been unthinkable to some after the bombings last year — a joyful, peaceful running of the world’s most tradition-bound footrace — appears to be Monday’s reality. And Rigsby, who was less than a mile from completing the marathon last year when the terrorist attack near the finish line killed three and injured more than 260, will run the marathon accompanied by two amputee veterans and a survivor of a traumatic brain injury.

“It’s a very surreal experience,” Rigsby said. “It is that celebration of God’s grace and me dodging a bullet, but it’s a celebration of the resiliency of this city and the resiliency of this country.”

Rigsby is one of 496 athletes from Georgia signed up for the marathon, up from 363 last year. This year’s field is about 36,000 entrants, 9,000 more than last year. The following are the stories of a few, including Rigsby, determined to return to Boston.

Aid for the wounded

Perhaps fate rescued Rigsby at last year’s Boston Marathon. Rigsby was nearing the end of the 26.2-mile race when he said he heard a voice telling him to take a break at the rest stops.

It would not be unreasonable, beyond the fact that he was running a marathon. His kidneys were failing to the point that he would require hospitalization after the race. But Rigsby is not one to submit to pain — he once finished a Georgia Marathon despite ill-fitting prosthetic legs that caused him to have to unfasten the legs every four miles and dump out blood. Still, Rigsby heeded the message and took breaks at aid stations with his running guide Laura Barnard. It’s possible that the rests saved his life — without the stops, Rigsby said his pace would have put him at the finish line, on the side of the street where the bombs exploded, at the time of the explosions.

But Rigsby’s presence may have also served a greater purpose. Rigsby’s foundation is committed to serving individuals who have lost limbs or mobility, which it does through outreach to amputees, grants for research and rehabilitation programs and providing education, counseling and physical and vocational rehabilitation for amputee veterans.

Soon after the marathon last year, Rigsby and Scott Rigsby Foundation executive director Scott Johnson determined that they wanted to play a role in aiding the wounded.

“It just seemed to fit the model,” Johnson said. “It’s kind of what he’s all about.”

Rigsby, 45, lost his right leg as an 18-year-old in Camilla when he was riding in the back of a pickup truck that was hit by an 18-wheeler. The impact thrust him underneath a 3-ton trailer and dragged him more than 320 feet. He underwent 26 surgeries, had his left leg amputated, battled depression and drug addiction before his recovery led him on a path toward becoming the first double amputee on prosthetics to finish the 140.6-mile Ironman distance triathlon.

His foundation’s Aid for Boston campaign raised more than $350,000 for the Spaulding Rehabilitation Network in Charlestown, Mass., which has gone toward the long-term care and research programs for the survivors who lost limbs as a result of the bombing and the expansion of Spaulding’s rehabilitation unit.

The foundation also enabled those survivors and their families to attend a national amputee conference last summer where Rigsby was the keynote speaker. Speaking earlier this week, he said he planned to visit with some of those families Saturday, opportunities to speak truth and encouragement into their lives. And then he’ll run the marathon, teaming with others who have overcome similar obstacles.

“I want to continue to create stories,” Rigsby said.

Triumph of spirit

Mark Coughlin had revered the Boston Marathon since first reading about it as a high school freshman. Last year was his eighth, and, at 49, he thought it might be his last. Then the bombings changed his mind.

“I knew once that happened, I knew I would have to come back,” said Coughlin, a music and video producer from Lawrenceville who is a track coach at Peachtree Ridge High. “I don’t know. You just have to show evil that you’re not going to budge.”

His two brothers, Michael and David, will be among the spectators. His sister, Deb Coughlin, qualified after not having run a marathon in several years, Coughlin said, as did his niece, Brianna Cash. Coughlin, a two-time winner of the Atlanta Marathon and an Atlanta Track Club member, went from giving up Boston to having a family reunion there.

After he decided to return, Coughlin said, “I knew it was just going to be a great year. A solemn year, but a celebration of good, a triumph of the human spirit.”

In the right place

Bryan Koepp was in Boston last year to watch his wife, Amy Bartholomew-Koepp, run Boston with a friend of hers. He and the friend’s husband went to the finish line on Boylston Street to watch their wives finish. Koepp wanted to watch on one side of the street, but his friend suggested using their passes to watch from the bleachers on the other side of the street. One of the bombs exploded right about where they might have been standing.

The fateful decision is never far from his thoughts.

“I’ll be driving, or I’ll hear a pop like fireworks or something like that,” said Koepp, an attorney from Cumming. “(It) has faded to a degree, but, yeah, it’s still there.”

On Monday, Koepp will run Boston for the first time, along with his wife, a member of the Atlanta Track Club’s competitive team who will run Boston for her fourth time.

“It was important for me to go back,” Koepp said.

It was truly traumatizing. He remembers a “Niagara Falls of bricks and glass” and how everything froze after the second bomb. He felt helpless not being able to provide medical assistance. He temporarily lost his hearing from the blast, but at first refused to go to a hospital because he thought there were other survivors who needed medical attention more than him.

His hearing returned. Amy, a veterinarian, and Bryan both became CPR certified. Bryan, also a runner, thought he might return to watch his wife run in 2015, but the Boston Athletic Association, which governs the marathon, opened about 500 spots in the 2014 race to those impacted by the bombs. Bryan waffled on whether to enter and submit an essay, but finally did, and was awarded a spot.

The Koepps, both 39, will be joined in the race by another family member — Amy, who had been told she had a 10 percent chance of conceiving, is 5 1/2 months pregnant with the couple’s first child. Her doctor cleared her to run.

Said Amy, “It’s kind of been a wild year for us.”

These are good days for the Koepps, who a year ago avoided potential death seemingly by chance. “The way that I just deal with that is I’m meant to be here, and I believe that I was taken care of on that day a year ago, so it’s my responsibility to live,” Koepp said. “That’s what I’m going to do.”

Show of defiance

Karen Cunliffe calls it “silly” and “just my little thing.”

She qualified for Boston by dropping 23 minutes off her personal best to help make a statement. She was in Boston last year to watch her daughter, Alex, run a personal-record time, sharing in her excitement that turned to sobbing upon realizing what had happened. Karen, an Atlanta resident, remembered text messages from running friends saddened that the Boston Marathon would never be the same.

And that’s why Cunliffe wanted to run Boston. Alex, who is earning a Ph.D. in medical physics at the University of Chicago, called her a few days later to tell her that she had to run Boston again. Karen didn’t feel a similar compulsion, but then told her daughter that she would, too, in a show of defiance that terrorists couldn’t steal the joy and celebration of the Boston Marathon, from the city, running community or her daughter.

“It was important for me to run with my daughter this year and with everybody, kind of do the in-your-face kind of thing,” she said.

But it meant training as she never had. Cunliffe, 55, rigorously followed a training schedule. She pushed herself to quicken her pace and woke up early for 5:30 a.m. runs in the summer in order to run a time of 4 hours, 5 minutes. She traded text messages with Alex after her runs, sharing updates of their training. And, on Sept. 8, in Bethlehem, Pa., Cunliffe finished a marathon in 4:04:18.

While her age group’s cutoff time was 4:10, the Boston Athletic Association, anticipating a crush of applicants, put in a plan to give priority to faster runners. “I was jumping up and down,” said Cunliffe, an accountant at her husband’s real-estate development firm and a grandmother of five. “I was telling people. I was telling strangers.”

Cunliffe doesn’t consider herself brave and doesn’t expect everyone to understand her zeal to run Boston this year. That doesn’t matter to her.

Said Cunliffe, “It’s just going to be an incredible time.”