When a friend arrived with lunch he went to greet them and fell over.
"I got up and went down for good — flat on my back. It felt very comfortable."
Renee Patterson got to Martin, put him in the recovery position and called an ambulance.
"Both ambulances were out of town so the paramedic team came to me. It was a blur."
The only evidence of the blow from the rock was a drip of blood on his ribs.
However, unknown to first responders, the percussion waves from the blow between his ribs had exploded an artery, inches inside his ribcage.
It was a fast trip to Te Nikau Hospital in Greymouth, where a medical team awaited.
The medical team drained the hospital's blood bank trying to keep him alive, and cut him from the base of his sternum and around his chest to the top of his spine to access the internal bleeding.
Incredibly, they removed two litres of blood from his chest (the average adult has five litres).
"By this stage my family was arriving.
"In theatre they took a lot of blood out of my chest. I was given 31 blood transfusions.
"They had to fly more blood in from Buller and Christchurch to renew the Greymouth bank. I am very thankful for the New Zealand Blood Service."
"Te Nikau saved my life with everything they did. They fixed the artery and dealt with the main bleed. They did the most amazing work for a team of a very small hospital and it needs to be recognised."
But at the time, Martin's family were told to say goodbye.
It was dire, he recalled.
"My chances of survival were pretty low and very hard for parents and [partner] Phoebe [Wilson] to hear.
"Te Nikau prepped me to be flown to Wellington. Throughout the procedure it was shifting as to if I would lose a lung or part of a lung, depending on if they could get bleeding under control — and they did."
Meanwhile, a surgical team from Capital and Coast DHB in Wellington had been flown into Hokitika and driven at speed to Te Nikau Hospital.
Wellington did not usually take West Coast patients, but for some reason he could not be flown to Christchurch, he said.
The team of surgeons stabilised him and, with more blood on board, got him back to Hokitika and into a waiting air ambulance.
"At that stage I was open, my surgical wound was only clamped. My grandmother, who is 82, came up to see me off."
In Wellington Hospital, the cardiothoracic team extended his surgical cut to gain further access and portioned off part of his lung injured by the rock's percussion.
"I came to in ICU and remember the breathing tube in my mouth — and the first thing I wanted was to talk. When they removed it I felt 100 per cent better. I remember a phone coming to me and it was my mother and father.
"I said, 'Hi mum, how are you?' ... This was 8.30am and I had just got out of surgery at 3.30am."
The incident with the rock had happened at 12.30pm, his first surgery had been at 3pm, he was airlifted at 10pm, arrived at Wellington Hospital at 1am, went into surgery and was awake again at 8.30am.
"I woke up with an upper and lower chest drain, a line in my neck going to my heart, four infusion lines, a morphine drip and a pain blocker to numb all the nerves which had been cut.
"They expected me to be in intensive care for four days — we were out in four hours."
From ICU he went into a high dependency ward. It was very sobering, he said.
"I was thinking how lucky I am to have lived the life where I have had full functionality.
"It was life-changing."
Martin was later flown from Wellington back to Greymouth.
"I can't fly commercially for a while because I have a pocket of air in my chest and cannot fly too high.
Supplies from the New Zealand Blood Service helped save his life, he said, and he now wanted to work alongside the organisation for blood donations on the West Coast.
— Hokitika Guardian