Friesen, 19, captured the incident in a video, which she posted to her YouTube channel, ShiCurves, on Jan. 26. In it, the Canadian vlogger attempts to try on a sweater and other clothing in the dressing room, but the female Walmart employee takes the clothes away from Friesen.
"Sorry, I'm really confused, what were you asking me not to do?" Friesen says.
"Just don't try to push it," the woman tells her.
"I don't understand," Friesen responds.
"Just don't try to put on something that's obviously not going to fit. That's all I'm asking," the employee says. "Just don't stretch it. That's all I asking. I'm not trying to impertinent or anything."
"I was so shocked I had to ask her to repeat what she had said, because maybe I would hear it differently," Friesen tells PEOPLE. "And of course, I didn't. But I quickly recognized that I was being discriminated against, and I was hurt. I felt anger, and vulnerability; something I never would have expected to happen to me. It brought out flashes of stories I've heard on the news, now only it wasn't some stranger being discriminated, it was me."
Friesen says in the video that she's since reached out to Walmart, and they've been very apologetic. She plans on sending her video footage and a statement to the company.
"Every single person from the Walmart team I talked to has been extremely sorry and extremely shocked that this even happened at one of their stores," Friesen says.
PEOPLE reached out to Walmart Canada to comment on the incident, who added that they had just become aware of it and were working on reaching Friesen.
"The only thing we know of at this point is the video," Alex Roberton, senior director of corporate affairs, tells PEOPLE. "But there's no record of her reaching out to the store or to head office at this point."
After PEOPLE informed them that Friesen says she's been in contact with Walmart corporate, he added, "One of our core beliefs is respect for the individual, that's certainly paramount. So obviously whoever she talked to [at Walmart corporate] is reacting appropriately. I just don’t have a record of those conversations here. We'll continue our efforts [to reach Friesen] on our end."
Roberton was unable to speak to any plans to fire the Walmart employee. "We wouldn't discuss that publicly," he explains.
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"People have had their opinions on what I should put on my body, but never have I been denied the right to try on an item," Friesen tells PEOPLE. "I've never experienced discrimination against my size, first hand."
"I felt vulnerable and almost like I was 'naked in a crowd,' so to speak," Friesen says. "But, ultimately it made me stronger. It gave me the fuel I needed to stand up against situations like this, and be that voice. Would I want it to happen all over again, no, but I can say it's defiantly given me a different perspective."
Now she hopes that publicizing her experience will stop anything like it from happening again.
"I think discrimination can happen to anyone, thick or thin," Friesen says. "That's another reason I made this public, because people need to be educated that discrimination can happen to anyone. Since making my story public on my YouTube channel, I have had viewers come forward with times they've been discriminated against and some of those stories are from being 'too thin.' "
"I am hoping this gives people the confidence to stand up to injustice and discrimination. It is my mission to teach people they have worth, and need to pride themselves enough to stand up and speak out about injustices in the world, that is my duty as a human."