The actress stars as Molly Dawes in the BBC One military drama series and says filming in the South African heat was a struggle.
Quizzed on This Morning she told Ruth Langsford and Eamonn Holmes: "It is really hard actually. I think that was probably the toughest thing out of the whole job, just getting used to the heat and stuff.
"But we did a week's boot camp when we got there and we started in shorts and then gradually as the days went on we added our combat bottoms and then the long sleeves and then your osprey and then your Bergen and then your helmet. So as the week went on you sort of acclimatised to it."
She went on to explain more about the experience, saying she has no doubt the real thing is even harder than what she went through.
"It's such an eye-opener, when you try and experience something that's similar but nothing like the real thing. I mean, just moving around is hard. If you imagine trying to get from A to B while being shot at, I just can't ... What they do is amazing."
'Our Girl' kicks off on Sunday, September 21 at 9pm on BBC One.
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