The man's wife ran into the store for help and Rose, who was working in the kiosk, rushed out to the car park while Josie called 999 for an ambulance.
Rose, who's 58 and was a carer for 30 years before joining Asda ten years ago, said: "The gentleman was very pale and very clammy and his pulse was weak.
"I just held his hand while Josie comforted his wife and made sure that he kept awake and didn't fall into unconsciousness. We had a bit of a sing-song and a laugh and I just kept him calm.
"After a while he started to feel better and his pulse and vital signs came back to normal. When the paramedics arrived they checked him over and said he was okay to go home.
"It was just one of those spur of the moment things really. I hope someone would do the same for me if I ever needed it."
The couple, who live in the town, wrote to the store for thank the colleagues.
They wrote: "We are immensely grateful for all the care and attention they showed us during this time.
"They are a great credit to your company and whilst we thanked them at the time we could not let the matter pass without putting our thanks in writing."
Rose and 37-year-old Josie, who works on checkouts, have both been nominated for Asda service superstar awards for their kindness.
Wendy, the store's community champion, said all her colleagues were proud of them.
She said: "In the wait for the ambulance there was care, giggles and banter given by Rose and Josie which, I'm sure, would have helped in making the couple more comfortable.
"They sent in a lovely letter thanking these two ladies. They are a couple of heroes. Well done ladies and thank you."