Mr Campbell was covered in blood and was unable to get to his feet, but Joel did not think twice.
He found a way to help the injured man up and into his house before going home and telling his mother. They went back together and helped Mr Campbell, alerting his family.
Joel was today quietly overwhelmed by the attention.
"I just went up to help him. When I had a closer look, there was a big bruise bursting out with blood," he said.
The 11-year-old said he tried to lift Mr Campbell without success but he found a way.
"I got a chair from inside and helped him on to the chair."
From there he was able to help Mr Campbell inside to clean up before running to his home nearby.
Mr Campbell never got to thank the 11-year-old. He was frail and unwell at the time of his fall, and died two weeks later, on October 9.
However, his son Peter said he was anxious that his rescuer be given a proper thanks.
"He was so grateful," Mr Campbell said. "He wanted to be able to acknowledge Joel and thank him for what he had done, and he wasn't able to do that himself."
What Joel did without a second thought for himself was a "good news story", particularly in light of negative reports these days of young people not caring.
"He didn't think, he didn't do a runner, he went and helped, pretty amazing as far as we're concerned."
- Greymouth Star