Four years ago, Patricia Crebase went out to the Broad Street Run to cheer for a friend competing in the 10-mile race.

"I got out on the route extra early, and I saw the wheelchair athletes go by," she said. "I just had that moment of, well, it's put up or shut up."

Crebase, an underwriter from Philadelphia, will be competing in the Philadelphia Marathon on Sunday. It is her first full marathon.

Crebase, 43, has MS, which was diagnosed in 1995, and she has been in a wheelchair for 10 years. She bought her first hand cycle on Craigslist.

"I wasn't great at sports, but I played them with a lot of enthusiasm," she said.

She did her first race in 2013 - the Hope and Possibilities Race in New York City, which is a five-mile event that raises funds for Achilles International.

The group is a nonprofit that helps people with all types of abilities participate in mainstream sports, and Crebase is a cofounder of the Philadelphia chapter. The group meets every Saturday morning at 2 Liberty Place, then heads out to Fairmount Park. They have 20 to 40 athletes meeting up each week, Crebase said. She'll be one of six Achilles athletes participating in one of this week's races.

"It's really emotional and overwhelming to see what's going on," she said of that first race with Achilles. She then did the Philadelphia Half Marathon last year, and the Ouch! Race, a 15K in Philadelphia, in August.

When she's not training with the group, Crebase usually works out in the gym or in Fairmount Park with a friend who rides on a bike next to her. Her favorite time of year for that is when Martin Luther King Drive is closed to traffic on Sundays.

"To have the whole street, and it's beautiful with the trees and things to keep you entertained," she said.

She chose this race not only because she knows it well, but also because the start is a few blocks from her Art Museum-area home.

Tough spots, she knows, will be at miles seven and nine, which are uphill.

"I go up them so slowly that I have time to build close personal relationships with the people on the curb," she joked. "Downhill is really fun. Uphill, not so much."

Athletes participating in the wheelchair race Sunday start at 6:57 a.m., three minutes before the elite runners.