Tina Muir stopped running after not having a period for nine years

Because of her lean physique and intense training schedule, professional runner Tina Muir did not get her period for nine years.

While doctors assured her she was completely healthy and would get her period back as soon as she stopped running, Muir, 28, was concerned about her health and the possible long-term effects.

“I was going to the doctors and they were just giving a one-off statement of, ‘Oh it’s just the running.’ They made it seems so simple, that all I had to do was stop running,” she tells PEOPLE. “As someone who runs for their career, it almost felt comical thinking about just stopping, but I would kind of push it out of my mind. Because I was young and not thinking of having kids, I was able to just go on with my life and say, I’ll deal with it down the road.”

When Muir got into her late 20s, she started thinking more and more about how her amenorrhea, or period loss, would affect her ability to have a family. That coupled with a few other factors led her to a difficult decision — she would stop running to gain weight and get her period back.

“I had achieved my lifetime goal, which was to represent Great Britain in the World Championship,” says Muir, who is from Great Britain but currently lives in Lexington, Kentucky. “I noticed that as soon as I did that, my motivation had been a little less and I found my priorities shifting. My sister had a baby, so the actual implications of not having a period were very visible. I was not feeling good, I wasn’t enjoying running. I’ve always been someone who believes you should follow your heart, and my heart was telling me that it’s time to step away and focus on my health.”

Although Muir doesn’t regret her decision, adjusting to her new lifestyle — and body — has been challenging at times.

“A big part of my identity is tied to myself as a runner, so it’s been a real learning curve, especially as my body is changing shape,” she says. “It’s tough at times to go against everything you’ve ever been taught. We’re taught how to lose weight, how to be healthier, and suddenly being told you need to loosen up and gain weight and relax seemed like it was wrong.”

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And while sometimes Muir gets caught up comparing her body to other runners’, she says for the most part she has been enjoying her new diet — and her new curves.

“It’s been nice to go out for a meal with my husband and scan the menu for what I actually want to eat, rather than thinking what would be nutritionally best for me and my running, or being able to have a few drinks at dinner,” says Muir. “I’ve been sleeping better, I’ve been happier, people have said I look like I’m glowing. I do feel more confident in not just who I am but how I look. I’ve actually seen my weight come on in all the right areas.”

“You would think being toned and lean you would be walking around on a cloud thinking you look amazing, but you still have those same insecurities,” she continues. “It’s actually quite liberating to be able to see your body as just a shell, and it’s been very refreshing to let loose of high standards and constant need for perfection, and accept that I can just be.”

Muir decided to share her story of recovery from amenorrhea because she knew other women would be able to relate.

“I knew how broken I felt going through this over the years,” she says. “Whenever anyone would have a conversation about their period or cramps, I would kind of hide in the corner because I didn’t want anyone to ask me, and I felt embarrassed. I was terrified people were going to accuse me of having an eating disorder, so I felt ashamed of myself. I just felt like if I was going through this, there had to be other people going through this.”

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After blogging about her experience, Muir has received comments from thousands of women who have their own experiences with period loss.

“The thing that surprised me is it’s not just runners or high-level exercisers, it could be anyone who’s lost more than 10 lbs., who trains really hard, who’s stressed out because of a move,” she says. “I knew I could help people, but I had no idea I would reach this many.”