The 38-year-old father-of-two, from Tallanstown, County Louth, is looking forward to taking part in a 5km memorial run in Dublin's Phoenix Park next Sunday in honour of those who have died.
While this mini run may be a walk in the park for many, it will be a milestone achievement for John.
In his 20s, he suffered a cardiac arrest and went into “cardiac arrest” on the operating table for 40 seconds, effectively dying and it was thought unlikely he would even live to see his 30th birthday.
John was born with a congenital heart defect and his mother died when he was 48. Despite being treated with medication and a defibrillator throughout his 20s, he continued to work at Largo Foods, makers of Tato Chips, and married his wife Claire, 36, with whom he has two children, Lauren, 12, and Sean, 10.
miracle
But as he entered his 30s, his condition worsened and he had to be on life support for eight days as his organs began to fail.
He recovered by Lauren's eighth birthday, but continued to struggle after that.
Last summer, his doctors put him on the waiting list for a heart transplant, and miraculously, within just three weeks, a compatible heart became available.
Now, just 13 months after his surgery, he says he's feeling better than he's ever been.
“I'm doing really well,” he told the Herald.
He walks 5km a day and also rides 20km a week on his stationary bike.
Additionally, he hopes to represent Ireland at the 2020 World Transplant Games.
He will always keep in his heart the generous donor whose organs gave him and six other transplant recipients a new life, and it is the memory of that anonymous donor that he will be memorializing at next weekend's race.
“I want to cherish this moment and give back. I wouldn't be here if a complete stranger hadn't saved my life,” he said.
John said he hopes his expression of gratitude will encourage more people to think about organ donation.
