Amputee Victim of Boston Marathon Bombing Returns to Run

-- For one participant in today's Boston Marathon, crossing the finish line will mean more than a 26.2-mile trek; it will be a vindication of her ability to bounce back from a 2013 event that ultimately cost her a leg.

Rebekah Gregory was at the finish line of the Boston Marathon when a bomb exploded in April of 2013. In a 2014 tribute run, she crossed the same finish line in a wheelchair. She was one of 16 marathon victims to lose a limb; after undergoing several operations, she ultimately had her left leg amputated and replaced with a prosthetic one.

But that didn't stop her from training for this year's Boston Marathon.

"This time I won't be laying on the ground in pieces, or having to be assisted because I can't do things on my own," Gregory wrote on her Facebook page in a post that received over 4,000 "likes" in less than 24 hours. "This time...the only thing hitting the ground will be my running shoe, as I show myself and the rest of the world that I am back, stronger than ever....and there is NO stopping me now."

Gregory wrote in an email to ABC News that she started strength training one week before her leg was amputated last November. Since her surgery, she has tried to train five days a week for at least an hour, focusing on both strength and endurance.

"Running has been a huge release to me with all of the craziness going on," she wrote.

Gregory has chronicled her journey since the marathon on social media. Before she underwent surgery in November to have her leg amputated, she posted a breakup letter to her limb on her Facebook page, writing, "go get yourself one last pedicure on me and enjoy it because tomorrow...I will be cutting you out of my life for good."

She then provided frequent Facebook and Instagram posts about adjusting to a prosthetic leg and her training routine as she prepared for this year's race.

Gregory posted on her Facebook page Feb. 2: "2 laps around a basketball court is still pretty far from a marathon. But do you know where else it's far from? Where I was a week ago." "Seeing progress every day and I'm only getting stronger from here"

Running with a prosthetic leg has been challenging, she wrote to ABC News, because she can't feel it hitting the pavement. She likened it to an "elbow grinding against a hard surface all day."

Gregory was also among the witnesses who testified at the trial of Dzhokhar Tsarnaev, who was found guilty this month on all 30 counts relating to the 2013 bombing. She told ABC News' Brian Ross testifying helped her overcome her fear of Tsarnaev, whom she called a "coward."

"I didn't realize I was so fearful, but I truly was and until yesterday, I had this sense of insecurity because of how much I had lost at the finish line that day and I took so much of that back," she told Ross in a March interview.