The silver and bronze medallist in the 200 metres breaststroke was suddenly asking what was the point of it all. Was it really worth the early morning trips to the pool and the miles and miles of training? The catalyst for this self-examination was the death of his father.
"It put everything into perspective," said the 29-year-old Birmingham swimmer, who represents Britain's best chance of a medal in the pool. "For a while it was difficult to find the real value and importance about being No 1 in the world at four lengths breaststroke. What does it really mean?"
The search for that answer included splitting up with his long-term girlfriend a few weeks before they were due to be married, serious consideration about retiring, and taking a year off from top-level competition.
"I had to find the desire for myself and want it for myself," he said. "I wasn't going to train for two years in the hope of getting an Olympic medal for my late father or my country but for myself. That's what I want to win it for.
"That might sound very, very selfish but if you don't want to win it for yourself, more than anything, you're not going to get it. That's the frame of mind I had to get into and I've been very motivated since I made that decision. It took a long break and a lot of soul searching to find the answer. I'm still here."
The time off? "I wanted a pressure-free year and a very long build-up to the Olympics. Although it looks like I've made a comeback, in fact I was training full-time. I just took a lower profile and stepped down from the European and World Short Course Championships to have a more relaxed frame of mind. I'd had a lot of stress and pressure in 1994 so I really needed that mental break. It wasn't a physical break."
Gillingham's rest followed nine years of expectation from a nation not exactly blessed with medal contenders in his sport. His first gong was won in 1986 when he came third in the Edinburgh Commonwealth Games but added to that was his Olympic silver in Seoul and a bronze in Barcelona. The focus is on him to complete the set this time with a gold.
This comes after an Olympics four years ago which left him profoundly dissatisfied. The bronze was hardly a memento to chuck in the nearest wastepaper bin, particularly as it was Britain's only swimming medal, but he had expected more and but for injury might have got it.
A groin strain collected in the morning heats meant he was handicapped in the final in the evening. The fastest man in the world in the 100m breaststroke that year, when he needed the speed his body could not give it to him. As he recalls, the fact he swam the fastest time in his life in the longer event later in the week merely deepened the annoyance. The form had been there; he was just denied access to it.
"If I'd equalled my lifetime best in the 100m I'd have won the gold medal," he said. "Because of the injury I didn't come away with even a tin can. That was very frustrating. I was still world No1 with the two best times that year yet I'd got nothing."
In the light of that, his chequered preparation for Atlanta is probably no bad thing. His time at the trials in March, 2min 15.15sec, was not hugely impressive and when he wanted to make the world take notice at Canet in France last month bad weather made it impossible.
The three-times European champion was confronted by a storm-tossed outdoor pool that produced conditions similar to swimming in the sea. His target of dipping under 2:14 was not possible and he will arrive in Atlanta with, at best, a world ranking of around eighth.
Nevertheless, he believes, and many others with him, that 1996 represents his best chance of winning a gold. "Eight years ago I had to beat the world and European champion with not a lot of experience behind myself," he said.
"In 1992 there was Mike Barrowman, who broke the world record a number of times going up to the Games. It was one of those events where the first three went inside the Olympic record by more than two seconds and we also swam lifetime bests.
"You can never stop anybody producing world record performances but I don't think that's going to happen this time. I think the event has plateaued an awful lot over the last four years. There hasn't been any significant improvement - the fastest time since Barcelona is 2min 12.2sec compared to the 2:11.2 I swam in the Games. If I can find the form I know I have, yes, I have a chance of winning."
Knowing that, and with a grievance against fate festering for four years, you would expect Gillingham to nurse less than philanthropic feelings towards his rivals. "I don't hate the other swimmers as I go to the blocks. Hate's a very strong word. I try to stay calm and philosophical.
"I try to take the view that all I have to do is beat seven individuals in the morning and seven at night. That makes it almost believable. In Barcelona I had that sort of strength of mind and I could enjoy the event because it didn't seem that overpowering. I was in control.
"I tended to focus on the support that was there for me, my team-mates, the people in the stands, the Union Jacks flying. With 11,000 people screaming and shouting there's probably about 11 there for you and you have to latch on to that. When you absorb the sheer noise it's inspiring. That's why I tend to do my fastest performances in a pressure situation. It brings out the best results."
In Atlanta, the noise, the pressure-cooker atmosphere, will be there. It is Gillingham's chance to milk it. And push the doubts to oblivion.Reuse content