When I was pregnant with my third child, I developed a condition called SPD (symphisis pubis dysfunction) that made standing or walking for too long excruciatingly painful. I was only four months pregnant and looked perfectly healthy, but I had to use the motorized carts at the grocery store to do my shopping. When I'd stop the cart and walk to a shelf to pick out an item, I often wondered if people questioned why I was using the cart. I wasn't elderly, and I wasn't injured. I barely looked pregnant and could clearly could stand and walk. Did they wonder if I was just lazy and selfishly taking the cart from someone who really needed it?

That was my first taste of what daily life can be like for the millions of people living with invisible disabilities.

I have friends and family members with rheumatoid arthritis, Ehlers-Danlos Syndrome, POTS (Postural Orthostatic Tachycardia Syndrome), and other conditions that sometimes affect their ability to move or be active. You can't tell that they struggle with pain or motility or exhaustion just by looking at them. They appear healthy, and they can move freely on some, or even most, days. But when they can't, they can't. They sometimes need assistance from canes or wheelchairs or other accommodations when their bodies flare up on them.

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A Facebook post from children's book author Kristen Waldbieser has gone viral for pointing out how such invisible disabilities can be overlooked or downplayed by others. Waldbieser has POTS, and she shared two photos of herself at a Disney theme park—one in a wheelchair with the caption, "This is me," and one where she's standing and posing with the caption, "This is also me."

She wrote:

"Yesterday I was at Disney, and I was using my wheelchair, which I need to go long distances (like a theme park). Anyway, I stood up to take a photo, and someone said (jokingly), 'Oh, the wheelchair is a hoax!' They quickly followed that they were kidding. However, the words stung with me. No, I don't need my wheelchair every day. But my wheelchair helps me get places that I otherwise probably couldn't go. But just because I don't need it every day, doesn't mean it's not real and it's not needed. It is not a hoax. And even jokingly, it's not ok to say that to someone. Not all disabilities or chronic illness looks the same. And it's time to break that stigma that those with chronic illnesses are faking it, which unfortunately, is heard by so many far too often. Long story short, you never know someone else's story, so please be kind with your words. 💖"

The person may not have intended any harm in their "kidding" remark, but it's not funny to jokingly accuse someone of faking their needs—especially because so many people really do assume that their conditions aren't really that bad.

Such assumptions are particularly prevalent for young people with invisible disabilities. Isa Fitzgibbons, 15, was 12 years old when she was diagnosed with juvenile rheumatoid arthritis. One day, she was using a wheelchair at the zoo when she felt the judgment from a group of college students. "They seemed respectful enough," she said, "until I got up to walk to the restroom. Then they started pointing and whispering, and I felt like an exhibit for them."

That incident stopped her from using a wheelchair in public for a long time. "It's a struggle to explain why you're limping, or how you're not lazy, you're just in pain—or why you're in pain," she says.

Ramona Gregory, 20, has both Ehlers-Danlos Syndrome and POTS. She's always been active—in fact, she runs her own cheerleading business. But her active life is spotted with days where just basic functioning is difficult, a reality that was particularly challenging in high school.

"I had a plan in choir class where I would sit down when I needed to since I couldn't stand for the entire class period without fainting," she told Upworthy. "The teacher was really cool about it. Kids around me though kept assuming I was slacking off and would act annoyed at me. Some kids would even follow my lead and sit down after me, although the teacher would promptly tell them to stand."

Gregory also says it's difficult for her to use a walker in public, even when she needs to. "I'm constantly afraid someone is going to say I'm faking it because I don't use it every day."

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Gregory's mom, Heléna, also has EDS and POTS (both can be inherited, though aren't always). She sometimes feels anxious about using a disability parking plaque, fearing people might get mad because she doesn't appear disabled. But that's not the only struggle.

"One of the really difficult things is being afraid of posting or sharing really awesome things you do because it looks like you're just living it up and not really disabled," she told Upworthy. "People don't see the preparation and the aftermath of participating in both normal functions and the fun stuff."

She enjoys mountain biking, for example, but only rides with her husband or by herself. "I can't just jump on my bike and go," she says. "My heart rate, blood pressure, and adrenaline are unpredictable, and I"m on and off the bike continually. I tried to ride with others but found I had to explain everything, like I was listing off excuses. Others would get annoyed. One time I ditched my bike and passed out on the side of the trail. The response was that I needed to get myself together because I was embarrassing the other riders in our group. People just don't get it, even when it comes down to actually losing consciousness."

"We spend a lot of time faking normalcy just so we don't draw attention or judgment. We hide what we do to avoid judgment," she says. "That's really it. People judge and that sucks."

It does suck. But hopefully stories like these will help more of us recognize that people are struggling with disabilities or chronic illnesses that we can't see and have no room or reason to judge anyone else's accommodations.