He believes he collapsed because his blood thinners weren't working.
"The blood could have stopped flowing, my arteries could have had [blood]clots. I could have been on my deathbed," were it not for the timely intervention of the supermarket employees, he said.
After his collapse, four supermarket employees, including duty manager and first aider Shannon Sibley, sprung into action by making sure his condition was stable and his privacy was maintained while the ambulance arrived.
"They put me in a wheelchair. In aisle eight, I was out of it. They closed aisle eight.
"They did an outstanding job. They deserve an award, they went above and beyond. It goes to show that Countdown do care for the community and the people who shop there. [I] just want to thank them."
Duty manager on the day and first aider Sibley is self-effacing about her efforts.
"The whole team pulled together. Which is what it's all about."
On the day of the incident Sibley put her first aid training to good use.
"Doug had a turn in our store. One of the team members called the duty manager because they noticed something wasn't right. The team member waited [with Doug] while I was got.
"I am the first aider, I was also the duty manager. It worked out quite well for Doug."
She called the ambulance, during which time a senior manager was called as well.
"Four team members were involved. Three with crucial parts and one was making sure that bystanders were kept away."
Appleby was stabilised in aisle four, while in his wheelchair, but Sibley noticed something wasn't quite right.
"When I was moving him through aisle eight to get to the agreed location that the ambulance was going to meet me. We wanted to put him somewhere private."
He was then transferred to the ground while the team waited for the ambulance's arrival.
"On my watch this was the most major thing which happened.
"We are grateful he is fine and he's got his family around. We are here if he needs support."