Four years ago Robert MacDonald was paralyzed. On Sunday he crossed the finish line at the Scotiabank Toronto Waterfront Marathon.

"It was truly emotional crossing that line," he told CBC News Sunday evening.

"I didn't set any records time wise, but man, it was special to accomplish that today."

MacDonald finished the 42-km run in five hours and 59 minutes — a feat he never thought possible after falling off a three-storey balcony in Mexico in 2012. He lost motor function below his waist, and doctors gave him a five per cent chance of ever walking again.

Sunday's race wasn't easy for MacDonald. Between the 17 and 30 km marks, he said things got "pretty tough" and he wondered if he should quit.

But at the 30 km-mark, his body began to feel better again. He also saw his girlfriend, which he described as a "light at the end of the tunnel."

"She was well ahead of me, and that gave me a little extra motivation too," he said.

"But my body felt a lot better for some reason. I don't know if it went into cruise control and said, you're going to finish this, but my general stride became strong."

MacDonald said he was motivated at the 30-km mark when he saw his girlfriend, Sarah, who was also running. (Submitted by Robert MacDonald)

'We're going to run a marathon one day together'

Three of MacDonald's friends ran the entire race alongside him on Sunday, which he said was hugely encouraging.

MacDonald said it was particularly special to run with one friend, Eric Humes.

"[Hume] had said to me almost four years ago, when I was lying in the hospital bed and I couldn't move anything from the waist down, 'We're going to run a marathon one day together,'" MacDonald said.

"And in that moment I said, 'Yeah right.' But I always kept it in the back of my head."

After an accident in 2012, Rob MacDonald lost motor function below his waist. He didn't know it then, but doctors had only given him a five per cent chance to walk again. (Submitted by Rob MacDonald)

Finished surrounded by friends

MacDonald said he crossed the finish line "swarmed" by friends and supporters.

"You really truly realize how special your friends and family are when your life is turned upside down," he said.

"Having all of them there that day, crossing the line, having them with me conquering this feat, I don't think I could have done it otherwise."

MacDonald finished the marathon "swarmed" by members of his running team, I Will. (Submitted by Robert MacDonald)

MacDonald ran with a team of about 120 runners, called "I Will," which aims to raise $150,000 for the Toronto Rehab Foundation.

To date, the group has raised $80,000.