Sioux City (ABC9 News)- Mary O'brien ran the Boston Marathon in 2013 to celebrate her 50th birthday. She was on the subway after having completed the race when the bombs at the finish line went off. As they evacuated the subway and returned to their hotel, she still didn't know what was going on.
"My son called and asked if we were okay and we said, ' yeah, why, we're great,' and he said 'turn on the tv' and we just could not believe it,” she remembers.
She wasn't going to return to the marathon initially, but after last years events... her mind was made up.
"Registration opened in September and whatever the first day was I got in the very first day."
This is going to be Mary's 80th marathon, so she has laced her shoes back up and is now back in Boston for Monday's race.
But, she knows this year is going to be much different. Runners have heightened security and aren't allowed to bring anything with them. Mary says that's huge. However, it's not going to stop anyone after last year.
"People are not going to let it hold them down, or hold them back. They're not going to live in fear. I think that's what you're going to see. "
36,000 runners are expected to participate and the city is preparing for roughly a million people at the finish line.
Mary says the end of the race is always the best part but she's curious what this year will be like.
"You've made it 26 miles and then you hear this huge crowd. And I think this year, I'm not sure how I'm going to feel. I think it'll be emotional," she said.