If a friend or loved one suffers with anxiety, it can be difficult to know exactly what they are going through and - in some cases - it can drive a wedge between you.
But it doesn't have to be this way.
Thanks to the internet, more and more people are opening up about their personal experiences of dealing with mental illness and, in the process, are helping others with anxiety speak out while educating those who do not understand.
1. Anxiety comes in varying stages and strengths
"Anxiety is sometimes in the background of my life, barely discernible, and sometimes standing right next to me, breathing down my neck," writes Kathryn Berens.
"It creeps up insidiously and then hits you with a winding force right in the solar plexus.
"The questions and the doubts then start: is this it? What have I really achieved? Why do I feel like I am standing still and everyone else is moving forward?
"Then the guilt sets in: what have I got to be down about - I am very lucky and have a wonderful life?"
She continues: "The thing about this 'mood' though is that usually it is not able to be attributed to anything particular - it is just a general feeling, often quite overwhelming, of sadness, emptiness and detachment."
2. It can come from nowhere, fast
As Dr Pooky Knightsmith puts it in a blog post on The Huffington Post UK: "We can go from feeling perfectly fine, to spiralling into complete panic, fast.
"It's unnerving...and often there is no explanation at all - or at least not one we can work out or articulate at the moment it happens."
But she adds that it is possible to help a friend or loved one with anxiety.
"Reassure us by finding a time when we feel a bit calmer and asking us about what we find helpful to regulate our anxiety," she explains.
"With these ideas, you can support us when things get suddenly harder. Things like breathing exercises, walking or listening to music might help - it's different for everyone."
3. It can be devastating
"Anxiety latched onto me in 2009 when I was going through a time that I want to forget," Lorna Weightman writes in a blog post on The Huffington Post UK.
"[It] started as a tight feeling; those butterflies that are not from excitement but from fear.
"I didn't want to leave home; I only felt secure and safe when I was in my own nest. I liked being in control of everything, if someone took that control away from me (which did happen) I lost it.
"The butterflies grew into a pain in my chest which hampered my appetite and more notably, my self-confidence. Anxiety was the friend that drained me. The one that hung out of me."
4. Opening up is really important
"I believe that opening up about our painful experiences can help everyone," writes Neil Hughes.
"It's helpful to us because we get to share our troubles with others. And it's helpful to everyone else because together we create an atmosphere where everyone can feel comfortable to share their troubles.
"Of course, such sharing must always be voluntary. Our experiences can be painful, and we may have very good reason to keep them private.
"But perhaps we might be able to find a safe way to share with someone we trust."
5. Anxiety has many triggers
"I can't always explain why it happens, why a dark fog just envelopes my whole being and slowly starts to smother me, why my thoughts turn against me, why I can't just 'put my face straight'," says Ruebi Bailey in a blog post.
"I wish I could, dear gods I wish I could...
"I wish I could identify what the trigger was (though I doubt it was just one thing), I wish there was a way in which I could just click my fingers and switch off the depression and anxiety."
6. You can't just 'get over it'
In a very personal Facebook post, Amber Smith opens up about what it’s like to suffer from anxiety and why we need to work to reduce the stigma surrounding mental health.
She writes: "It disgusts me that so many people are so uneducated and judgemental over the topic.
"They say that one in three people will suffer with a mental illness at some point in their life. One in three! Do you know how many people that equates to worldwide?!
"I’ve been battling with anxiety and depression for years and years and there are still people that make comments like ‘you’ll get over it’, ‘you don’t need tablets, just be happier’, ‘you’re too young to suffer with that’.
"F*** all of you small minded people that think that because I physically look 'fine' that I'm not battling a monster inside my head every single day."
7. People with anxiety still want friendship, but it's hard
"Anxiety makes us much harder to be friends with," writes Dr Pooky Knightsmith.
"We often change plans. If we do manage to turn up when we say we will, we may be very quiet, or angry or tearful and we may go home early or suddenly.
"Yet you continue to invite us, be patient with us and to be continually reassuring and supportive.
"This unconditional care and kindness can feel alien and perplexing to many sufferers of anxiety who simply cannot understand why you persevere."