According to the Cambridge dictionary, going with the flow is defined as to do what other people are doing or to agree with other people because it is the easiest thing to do.
I am writing a paper and I'm really stumped as to what would be an idiom, or a way to describe a person who is not going with the flow.
Specifically, the sentence which I need this for is this:
I have had to come to terms with a lot of cultural differences which has been a struggle for my ____________ personality.
Note: I am specifically asking about an idiom, and not words such as: inflexible, rigid, stiff, unadaptable, firm.