Never tell people your life story. Just tell them you have a rough time. That's it.
If I'm at work, everyone gets the vanilla "Everything's ok!" response, and especially so to patients. Coworkers, your cohort, clinical instructors, and patients don't need to know your business.
Leave your baggage at the door - once you enter school/clinical etc., watch your Ps and Qs
Completely depends on the situation. When I worked in peds neuro, for example, it didn't bother me that my colleagues knew that I had a history of a brain tumor. I did not tell them, however, when I had an MRI concerning for possible recurrence. I had colleagues at my next job, around my age, who had ulcerative colitis and Lupus so we often had discussions about medical issues. At my last job, I told no one except for the people I was closest to at the job on the day I have my notice which also happened to be the 16 year anniversary of my diagnosis. At my current job, I work with 4 other people. 2 of them also have chronic illness and we all know basic details of the others' diagnoses.
You just gave yourself the best advice possible. Follow it. Oversharing with colleagues is never a good idea. Oversharing with supervisors is an even worse idea unless there is a compelling reason for them to know the personal details of your problems, like needing to request time off to deal with said problems.
Telling a patient who's having a panic attack about my history of panic disorder helps them a lot with the anxiety of it. This is a problem that can cause agoraphobia, it can get serious. I get to be the proof that even with this disorder, they can be fine. I'm at the point of being an aide taking care of them while I have the same problem. It causes positive thinking about their long-term outlook on living with the disorder.
And if you're having problems that affect work, definitely share it with your supervisor the right way. Don't be afraid to ask your instructors for advice with how to cope with situations before they ever come up.
When you trust coworkers, it can be helpful to share some issues in case they need to help react. When i have a panic attack, my coworkers are quick and willing to help out so that I can take 5 minutes to calm myself down. In return, I help them when they need it. I never question helping them so that they can go get a snack.
Don't overlook the huge benefits of sharing the right personal issues at the right time. It can be extremely helpful for your work environment, and it can be very therapeutic for your patient. But it takes tact and common sense... and that common sense is basically the entire foundation of nursing.
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