"A marathon is a celebration of life and endurance and the human spirit," Rep. Kyrsten Sinema says. "Runners are such a tight-knit community. Even if we don't know each other, we treat each other like friends."

Next week, Sinema, a freshman Democrat from Arizona, will be one of just two Members of Congress running in the 118 th Boston Marathon, joining Rep. Joe Kennedy, III, D-Mass.

"Boston is like the Holy Grail of running events," she told ABC News. "I never thought I would ever find my toe at the starting line at Boston."

We run for #BostonStrong. Help us support @OneFundBoston, donate http://t.co/mS9Hzzk9uv pic.twitter.com/V2ExMNQnpi

- Kyrsten Sinema (@kyrstensinema) April 15, 2014

Sinema, 37, is running in honor of Martin Richard, the eight-year-old boy killed by the first blast in last year's twin bombing. She says she has raised $20,000 for Team MR8, a charity established in memory of Martin by his parents.

Of the 36,000 racing bibs available for the historic occasion, 5,500 slots are reserved for charity runners like Sinema, a self-described "endurance runner" who would not qualify based on speed. She said Martin's parents chose her and a friend to run in honor of their son alongside 98 other Team MR8 competitors.

"I'm so privileged to be running in honor of Martin Richard and for the other victims and survivors," she said. "That is a big responsibility to carry to that starting line and to carry those 26.2 miles across that finish line, so I'm going to spend those four-plus hours with Martin and the other victims and survivors in my heart."

While most members of Congress would probably struggle to run even one mile, Sinema says she has completed eight marathons as well as an Iron Man triathlon.

"This is going to be by far the most emotional marathon I've ever run," Sinema admitted.

For Kennedy, it'll be his first marathon. He is running with his wife, Lauren, who is raising money for Boston Medical Center, where she used to work. Kennedy, the great-nephew of President John F. Kennedy, is running for the One Fund, a foundation established by Massachusetts Gov. Deval Patrick to support the victims and survivors.

"This anniversary is not just about the city we were on that tragic day," Kennedy wrote in a statement this week. "It's about the city we have been every single day since."

Sinema is also holding several events this week in her district to continuing raising money for others touched by the tragedy. In addition to Team MR8, she says she has raised nearly $10,000 for One Fund, and $4,000 for the Multiple Sclerosis Society of Greater New England.

Sinema calculates that she runs about 40 miles per week at a pace of about 10:30 per mile. Her best finish came this January in Phoenix when she completed the P.F. Chang's Rock N'Roll Marathon in 4 hours and 29 minutes.

"If I'm having a good day on Monday, I can smash that record, so that's my intention," she pledged. "It's also the most exciting course in the world and it's going to be a really, really emotional day so I have my fingers crossed that that will bring me across the finish line faster."

So after last year's horrific bombings, is she concerned at all about the security surrounding the marathon?

"I have zero concerns about security," she said. "The City of Boston has done an incredible job preparing for this marathon and I have 100 percent confidence that it'll be a flawless event."