There will always be something that makes you want to quit, but we all hold on because there’s always something that will remind you why you chose this career.
Dealing with these emotions can be hard. You should absolutely consider therapy, even if it’s just to talk it out with someone. It’s much better not having to go through it all alone. Beyond that, working on replacing any unhealthy coping mechanisms you may have with healthier ones is a good way to go. Especially if you can do that before the going gets tough.
It’s important to remember that our medical professionals are a noble people and are always appreciated, even if the patient never explicitly says so.