How do you tell your coworkers/colleagues/managers that you need to take a mental health day?

🤣

Actually I don't. Being self-employed I just get paid for the amount of time I spend on working (within the reasonable boundaries, ofc), so when I really need I just take an unpaid sick leave for a day. Tell them I'm ill. They don't need to know, that's more of a mental healing than physical healing what I need.

You don't need to tell them. Mental situations are just the same as physical situations. You can call in sick if you need the day off, and they don't have the right to know what kind of condition you have that causes you to be sick (unless it's for prolonged durations, but considering you're talking about one day, you're completely in the clear).

If it's a longer standing condition, you might have to explain the situation in some way. If you've got decent people working there, they will want to see you back on your feet ASAP and making money for them again, and they will reach out to you if you need the support.

Hey, I've been pretty spacy/foggy/tired/burned out lately. I'm going to take a break tomorrow.

Be honest with your boss, no need to tell your colleagues.

In my personal experience I found my anxiety was worse when I took the day off using a random excuse as I was worried about being found out. After I spoke to my boss about it I was more comfortable while in work and had an easier time speaking to my boss if I needed to work from home or take the day off.

That being said, if you're not comfortable speaking with your boss about it, use an easy excuse. My recommendation is diarrhea, nobody wants to know anything after you say that word!
(Also its believable that it'd only last a day)

See you guys on monday... the first of June... 2020...

"I won't be there 'day'"

Use the words: "I need to take a mental health day, I am burnt out."

Just tell them the truth. "I have the 1 day cold. You know, the one that's been going around for 3 years.."

"I accidentally dropped a production table"
Just kidding, but if I come in today, I might!