When?

When do you decide to stop pursuing something when it doesn't 'fit' you? When do you decide to give something up, when it doesn't ring true to who you are? Or do you even give it up? When do you stick to that something until forever, or walk away from it, even though there's nothing else to walk to (that you can see)? When do you choose to keep at something, even when you know it isn't you?
Or really what I'm asking is, when (if at all) is it right to do any of the above? Is it okay?
Is it okay to walk away from something simply on the basis of it not fitting your personality, your innermost 'you', or are you just being selfish?
I'm pursuing a career that requires certain things of any (good) nurse to do, that are quite contrary to my personality. Not so much contrary actually. It's just that my personality feels limited and confined in a sense.
No, it's not that it either. I can't explain it. I tried explaining it earlier to some people, and it just wasn't working.
It's such a hard thing. Because every week, at the very least, I come face to face to these questions, because I have clinicals. The other days, I can push them back...but on this one day, I can't.
I want to feel true to myself. And yet, how much of "being true" to oneself is just another way of just saying "I don't like this".
But even if that's what I'm saying, shouldn't that tell me something? Because I know that it's not that I'm lazy, or uncaring, for not feeling okay about working as a nurse. It's not that at all. In fact, I think I care too much sometimes. I care too much about the moms, the babies, if they are in pain, if they are thirsty, if they slept good, if they are lonely, etc etc etc. all the time. I'm too aware of the little nuances, from the lonely housekeeper man stepping into the room who needs someone to talk to, to the wealthy guest who is sitting in the room, who seemingly lacks nothing, and yet has an emptiness in her eyes that I want to take time to find out about, and somehow make go away.
A little stress can be good, but a lot of stress, is not good (for me). And that's what I feel that nursing has to offer me. It's not the physical stress, the busy kind of stress, but the relational stress that it causes me that is bothering me.
I am so much of an introvert. I am a helper, not a leader. I am independent. I can work on my own just fine. I can work with people too. I love working with people. I just take way more into my brain about everything and everyone around me than most of the others. And so I get mentally exhausted a lot faster/easier than most.
It is very hard to explain my thoughts right now.
I think I am done for the night.
When do I -or do I not?
Sincerely, Sara