Expression: to wear a hair shirt 24/7

[Torsten]

Hi, have you ever heard the expression to wear a hair shirt 24/7? Based on the context the phrase occurred, I have an idea of its meaning but how popular is this expression? Here is the sentence I'm referring to:

Submitting a print book to conventional publishing houses or to agents is similar to wearing a hair shirt 24/7. No matter how good your book actually is, or how many critique services and mentor writers have told you that "you've got what it takes," your submitted manuscript keeps coming back to you as if it is a boomerang instead of a valuable mine of information.

Hope you are not wearing a hair shirt right now.
Thanks
Torsten
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Test Of English for International Communication
TOEIC Preparation & TOEIC Vocabulary

[Jamie (K)]

This is a combination of two popular phrases: to wear a hair shirt, and 24/7.

A hair shirt is (was?) a scratchy shirt that monks and nuns used to wear for religious self-mortification. (Some people in the religious order Opus Dei even now wear a small, prickly leg band for a couple hours a day for the same purpose.) Sometimes we say someone wears a hair shirt when we want to indicate that he intentionally inflicts some kind of torture on himself.

The term 24/7, as you know, means 24 hours a day, 7 days a week.

So the author was just trying to say that someone was torturing himself nonstop. I've heard both expressions, but I've never heard them used together.