We all know people who just can't seem to cry. They are usually men, although women aren’t immune to this issue entirely.

We all also know that everyone gets sad sometimes, so it's perplexing when someone is unable to shed tears, especially if it's someone close to us, like a romantic partner or a sibling. We may assume they must be ‘shutdown’ emotionally, and that they need to learn how to get in touch with and express their feelings. Or worse, we may be afraid they're deeply depressed, possibly even suicidal.

After all, isn’t the inability to cry a sign of depression?

Why can't cry even when I'm sad?

There are certain medical conditions that can cause an inability to cry, such as decrease in tear production known as dry eye syndrome (keratoconjunctivitis sicca) and an autoimmune condition known as Sjögren’s syndrome.

But most of the time, there's nothing physiologically wrong with someone who can't cry. Instead, it's their beliefs about crying that are getting in their way. Specifically, many people who can't cry could do so, but they've been taught to believe crying is a sign of weakness, and that strong people don’t cry.

In other words, many people who are unable or unwilling to cry have issues with vulnerability.

Dr. Brené Brown, storyteller, author and research professor at the University of Houston, defines vulnerability as “uncertainty, risk and emotional exposure.”

RELATED: How To Get Over Your Fear Of Vulnerability In 6 Steps (Even If You've Been Hurt)

Think about it, what could be more vulnerable than bawling your eyes out?

Until, and unless, these people change their beliefs about crying and what it means to them, they will continue to act in the same way, unable to cry or otherwise express themselves when they are sad or upset.

I was one of those people, so I know intimately what it’s like to not being able to cry.

I was born with normal tear glands, but because of a childhood accident, I lost my ability to cry. It took me 21 years to learn — or rather, to re-learn — how to cry.

I had a scalding accident when I was 12 years old. I ended up with second-degree burns on my hands and forearms and my parents rushed me to the hospital. I remember sitting in the emergency room bawling my eyes out from the pain and confusion.

Instead of comforting me and telling me everything was going to be okay, my dad looked me straight in the eye and told me to shut up.

I was so stunned that I stopped crying right away. And, at that moment, I made a decision to never cry again, at least, not in public.

For the next 21 years, until my dad passed away when I was 33, I cried very, very rarely. It was like a once-a-year event for me.

And I certainly didn’t cry in public. At all.

It wasn’t that I didn’t get sad. I did. But I had basically shut down and lost the ability to cry.

In the instant when my dad told me to stop crying, I made up a story in my head that crying was weak and that he was ashamed of me. Never mind that this was completely non-sense; what mattered was that I believed in it.

RELATED: What Guys Think When They See A Woman Crying

In the meantime, as my dad got older, he lost his fiery temper and we grew really close.

And when he passed away, the floodgates opened.

I spent the whole year after his death crying. I cried everywhere — at home, at work, in shops, while hanging out with my family and friends, and even when I was driving ... which, by the way, was a health hazard, because I could barely see the road!

I was an inconsolable, sobbing mess, but I was grieving a loss so great I didn’t care what other people thought.

On the other hand, even though a large part of me was sad, a small part of me was relieved. I felt like I finally had permission to be myself again. The real me was a lot more ‘girly’ and softer than he wanted me to be. That was the part of me who would cry when she was upset, rather than stuffing it down and putting on a brave face.

Fast forward another eight years, and these days I’m a big advocate of having a big, messy cry for myself as needed.

RELATED: Confessions Of A Constant Crier (And Why You Should Stop Apologizing For It)

While crying probably won’t resolve the actual problems any one of us are dealing with, it does discharge much of the pent-up stress and tension in our body and mind, and this makes us feel better, calmer and more clear in the moment, so why not let the tears flow?

Here are three ways to encourage yourself or someone you care about to overcome an inability to cry.

1. Suggest starting with baby steps.

To start with, help them give themselves permission to cry in private, or when they are watching a sad movie or reading a sad story. This way, they are free to be vulnerable without worrying about what other people might think. By giving them the chance to externalize the source of their tears, they don't have to compromise their self-perception of being the strong one. Instead, they can blame their tears on that movie or story!

Then, when they become more comfortable shedding a few tears, they can start showing their vulnerability with close family and friends, and later with other people.

2. Share the benefits crying offers.

It may seem obvious to you and me, but for people who are not used to crying, they might not be aware of its many benefits, such as releasing tension in the body, relieving stress, improving mood and boosting communication.

Help them to see it simply as a useful tool to regulate their emotions, without all the unnecessary mental ’baggage’ or story.

3. Challenge them to challenge their beliefs about crying.

Ask them to think of people they admire who cry when they experience sadness or other negative emotions. Alternatively, get them to brainstorm situations where they're willing to admit that crying is absolutely warranted.

This will effectively contradict their old beliefs about crying and provide positive evidence that vulnerability is not weakness and it’s okay to be vulnerable. Over time, it will help loosen the hold these beliefs have over them.

Imagine the people in your life, especially those closest to you, are finally able to cry when they are upset.

They feel comfortable and safe being vulnerable, instead of trying to be strong all the time. They are no longer shutdown emotionally. They are in touch with their whole range of emotions — the good, the bad and the ugly — and they express them to you and others they trust freely and willingly, inviting everyone into their world.

At the end of the day, there's nothing more freeing for people than being able to be ourselves and not having to stuff everything down in order to put on a brave face for everyone else.

RELATED: Crying To Your Favorite Sad Songs Has A Surprising Benefit

As a lawyer-turned-relationship coach (following her own devastating breakup) Annie Huang helps women bounce back from difficult challenges and heartbreaks with ease. Download a free chapter of her recently published book "Brave Again: Your Roadmap from Heartbreak to Happiness", a book about healing and finding courage to begin again, or visit her website for more.