After the Rio Games in 2016 Murdoch was ready to walk away but changed his mind. Then, at the start of lockdown, he wondered whether he had it in him to keep on training with so much uncertainty.
Twelve months later, he’s glad he did.
“To be on my second Olympic team and be considered a double-Olympian, I’m dead chuffed,” he said after his selection was confirmed this week.
Now 27, Murdoch is one of the elder statesmen in the Team GB swimming squad and is the senior Scot alongside Duncan Scott, Kathleen Dawson, both 23, and Cassie Wild, 20.
He will go to Japan to compete in his favoured 200 metres breaststroke and is targeting a place in the final. After that, who knows?
“To make a final at the Olympic Games in this event now would be a seriously special feat,” said Murdoch, mindful of the rise in standards across his discipline.
“My aim is to make the final and you only have to look at Rio when the guy who won it was in lane 8. I’ve won a bronze medal from lane 8, there’s no reason why if I was qualified in lane 8 I couldn’t get in amongst it.
“That’s the aim, make the final and then take it from there.”
Dmitriy Balandin was the surprise winner in Brazil five years ago, stunning the other finalists to become Kazakhstan's first ever Olympic gold medallist in swimming.
Murdoch competed in the 100m in Rio, reaching the semi-final, but it was the Adam Peaty show in the two-lap event, the Englishman winning gold in a new world record time of 57.13 seconds.
Murdoch, a 200m gold medallist on a never to be forgotten night at the Glasgow Commonwealth Games two years earlier, returned home from Brazil to take stock.
“Post-Rio was pretty bad,” he admits with admirable candour. “I thought I’d call it a day there.
“And this time last year, a few weeks into lockdown I was thinking - can I really see myself hacking through this for another year? I really wasn’t sure if I wanted to.
“I had an asterisk beside my name on the British Swimming funding because if I didn’t make the Olympic team, I’d lose my funding and that’s a tough place to be, it puts a little bit more pressure on you and I was thinking do I really want to be the guy who was hanging on or do I want to go out on my terms?”
Murdoch credits his involvement with the International Swimming League for giving him the motivation to carry on.
“It made me realise how much I enjoy swimming and how much I’ve got left to give. Having the ISL on the horizon changed my mind. And knowing other people had confidence in my swimming ability, probably more confidence than I had at the time, definitely kept me going.
“There’s definitely times you think about retirement but I’m maybe just at that age – people expect you to chuck it in swimming when you get to 27, 28 but people are getting older and I just need to keep reminding myself of that.”
Much as he is thrilled to be back on the Olympic stage, the Balloch-born Murdoch is not sure anything could top his stunning Commonwealth Games victory. Winning gold at a home games, and beating Olympic silver medallist and fellow Scot Michael Jamieson in the process, was one of the most memorable moments of Glasgow 2014. It was also Murdoch's first major gold medal.
“2014 is hard to top, even if I was to win a gold medal this summer, I’m not sure it would top 2014 because back then, there was just so much that went into it and so much that happened,” he said.
“It was my grandad’s 70th birthday, all my family were there, it was in Glasgow, the stars aligned and it was the perfect day so I think it will be really hard to top that. I don’t know if that’s a positive or a negative thing for my swimming career but I think it’s the moment I’ll look back on and think that’s the most special thing in my swimming career.
“In terms of making my second Olympics, there’s a lot that has gone into this one. There were a couple of tough years when I couldn’t make the team in the 200m.
“So thinking about everything that went into making this Olympics, I’d say it’s definitely top three [achievements in my career] – there’s winning the Commonwealth Games, winning the Europeans a few weeks after not making the 200m breaststroke at the last Olympics and then probably this, if I had to rank them.”
Murdoch’s combative instincts have not been blunted by age and experience. When asked if he ever considered if any of his rivals had a history of doping, he offered a fascinating insight into the competitive edge that makes him such a warrior in the pool.
“When I get on the block, it’s the last thing on my mind,” he said. “I’m not thinking about anyone’s history. When I’m standing there, it doesn’t matter who’s next to you, I look left and right and am like, ‘come on then, let’s have a square go right now. Draw a line in the sand, let’s have a square go’. That’s how it is.”