The Scottish distance runner already had a certain inner steel and now likens herself to Arnold Schwarzenegger's iconic cyborg creation after acquiring a bit more in the aftermath of a broken ankle in January 2015.
"I already had five screws in my left foot and now I have another two and a metal plate in my ankle," the 25-year-old from Dundee explained. "It is almost like a robot foot - I am slowly turning into The Terminator.
"I don't set off airport scanners yet, but it is certainly getting that way. It is just really unfortunate that it has always been my left foot."
A top-two finish in Sunday's 5,000m at the British Championships, doubling as Olympic trials, would secure a place in the Great Britain team heading to Rio - a fitting reward for persistence in the face of adversity.
As McColgan relates the "long process" of recovery from the initial ankle break, to further surgery last July, to jogging again, to issues with "compensatory injuries" and additional nerve problems, it is not hard to understand her surprise at the form she takes to Birmingham.
The Scottish 3,000m steeplechase record holder has ditched the hurdles and water jumps to protect her vulnerable ankle and run personal bests in the 3,000m and 5,000m - the latter in her first track outing for 22 months - to achieve the Olympic qualifying standard.
"It has been an absolute blessing to come back as quickly as I have," she told BBC 5 live's Sports Panel recently. "I honestly thought this year would be just about slowly building things up and just being happy to be running again.
"But my form has come back quite quickly. I put a lot of work in on the cross-trainer and in the gym and pool. I did everything I could apart from running.
"It is nice to be back running PBs over all distances and I am ready to race the trials now."
Steve Cram, BBC Sport's athletics commentator, saw first hand what McColgan went through at a winter training camp for some of Britain's distance athletes in early February.
"I have got a lot of time for Eilish," Cram told BBC Scotland. "I was with her in Kenya and she was still struggling then.
"But she never gives up on it. Everyone else was going out and doing their miles on the trails and Eilish was not able to run much at that point, but she was going into the gym and running on the machines.
"She threw herself into that rehab with an incredible amount of energy. Her motivation stayed high and that is why she has come out the other end of it.
"We have got three or four girls who are doing well at the 5K this year, but if Eilish can re-produce her form at the trials, hopefully she will be in Rio."
Fellow Scottish 5,000m runners Steph Twell (14:59.00) and Laura Whittle (15:08.58) have both run faster this year than the 15:09.94 McColgan posted in California in early May.
But, given her rapid progress since returning to the track, you wouldn't bet against her, even if she admits the reward of an Olympics spot brings added pressures.
"Preparing to put on a GB vest is completely different for me to competing in a Diamond League or a smaller race," she explained.
"The Olympics is the pinnacle of sport, it is what you spend years training for and dreaming of.
"It is definitely a lot more intense and there are a lot more nerves on the start line knowing the opportunity to make the team is up for grabs.
"It is like another level of competition up, but it is one you have prepared for.
"You are still running and racing and doing exactly what you have trained to do. But the whole environment is a little bit more pressurised."
McColgan has already competed at an Olympics, missing out on the final of the 3,000m steeplechase in London four years ago.
She concedes switching to the 5,000m so close to Rio is "quite a scary change"- particularly in such a competitive event. But, considering the alternative, the risk-reward decision became clear.
"I can run and get through the aches and pains of my ankle, but the impact of jumping in the steeplechase is just too much of a risk," she said.
"It is my favourite event, but if it meant I had to sit on the sidelines for another year, I think mentally it would have been very, very difficult.
"I just love running and it would have been silly to risk it to try to make the team for Rio. I just wouldn't be confident mentally."
If McColgan requires any further inspiration on the road to Rio, she only has to look at her coach, and mother, Liz McColgan-Nuttall.
The 1991 world 10,000m champion, two-time Commonwealth gold medallist and London Marathon winner, who also won Olympics silver, was famous for her belligerence and grit.
"My mum is a huge inspiration to me," says her daughter. "So many people come up to me and say 'I used to watch your mum running 25 years ago, it is amazing to see you doing it'.
"She is still inspiring people today. It is really nice to hear that about someone who's not just your coach but your mum.
"There is something very different about her persona. She is very motivated and hard-driven. She was just so dedicated to what she did.
"It is a mentality thing. She has got a fighting mentality and that is what makes people legends in their sport - they have a different mentality to other people.
"You don't know why that is or how it has happened, but there is something unique about them."
And possibly their offspring too.
Bringing home precious metal from Rio would be a huge stretch for McColgan or any of the Brits in a women's event dominated by the leading Ethiopians and Kenyans.
But just getting there at all would be cause enough for celebration.
'I'll be back' could have been Eilish McColgan's personal mantra over the past 18 months - even when the doubts and demoralising setbacks continued to afflict her.