First of all, I don't like to be pressured, as I imagine most people don't, but I don't have the immediate resist at all costs response, either. I know my mom & sister knee-jerk to "Hell no!" & won't even consider what is being pressed upon them. I have never been like that, but being approached that way does get my dander up!
I usually just outright address the fact that I won't accept them pressuring me & don't appreciate that they'd try. Regardless of their motive, I want to be treated with respect and that includes showing me the that you respect my intelligence enough to listen & weigh your suggestion appropriately without trying to manipulate me. I cannot stand someone with the attitude that they know better than I what is best for me! How arrogant & insulting!
So, I never give in just to shut them up and frankly, that would never occur to me as an option. But, I also don't go to the other extreme. I consider what their motive might be in coming across so strongly. That can be important, especially when it's family. For example, some parents have trouble recognizing their adult children's autonomy & might fall back on old patterns of "persuasion". If it comes from a place of genuine concern, I can get over it more easily.
I always do my best not to be pressured into making the decision or commitment they want at that time. That way, I have time to cool down from being annoyed and can seriously consider what they said. If they have insight into something that benefits me, or they otherwise were on the right track, then I have no problem accepting that and altering what I do or think.
I am always considering new input, discarding what doesn't help & changing my view if new evidence is compelling - I see no shame in changing my stance when new information comes to light. I can only base my conclusions on what info I have at hand. If I find more, I add it in & see how it meshes. I am capable of learning, but don't want to be led there by the nose. I can say, "You know, I hadn't considered that" or, " I never looked at it like that and you're right..."
But, if it is something I disagree with, I do not leave it up for discussion. I am not going to change my mind just because they want me to, or because they came to a different conclusion & that's fine with me. I am not threatened by someone disagreeing with me, but I am not going to try and change their mind, nor be pressured into defending my opinion. While I like to relate to someone over the things we agree upon, I don't need to agree upon everything with them, nor do I feel the need to challenge them if I don't agree. I can let it go as long as it's of no consequence to our interpersonal relationship.
If someone repeatedly persists in pressuring me, then I simply stop giving them the option of doing so. If that means not interacting with them at all, or just refusing to be led into conversations about certain topics, that just depends on their level of intrusiveness.