My manager is very impatient and often criticises me. I cant take criticism well and have a low threshold of stress. What can I do to get stronger (to cope) on my own and without changing her at all?

I'm sorry to hear that your manager is criticising you like this. The first step in managing this situation is to consider if the criticism you are receiving is reasonable. That is not to say by any means if it is deserved, but is the criticism delivered in such a way that it promotes growth? Or is it aggressive and demeaning? Is the criticism related specifically to work, or is she making personal attacks against you? How do your coworkers feel about this manager? Regardless of the reasoning behind the comments, it is clear that the way she is going about communicating with you is causing you some distress. Aggression from management does not foster an environment that is conducive to success in the workplace. You have a right to feel safe and comfortable in the workplace, and should not have to force yourself to endure distressing behaviour from your manager. I understand that it may seem impossible to change her, or that it's just easier to cope with it. In the past I have endured workplace harassment because it was just easier to not bother taking it further. Maybe have a chat to your coworkers and see if there's a possibility of going up the managerial tree to discuss the issues, and if they will support you in that. As I don't know your location, I can't really advise exactly, but most countries have unions that you can seek advice from, or a Fair Work governing body that protects worker's rights. If it is causing you this level of distress I would reccomend having a look into those options. I wish you the best.

Criticizing people or their's work is not healthy in any environment. You might be trying hard to perform your task sincerely and try to improve. When people try hard to improve but the people instead criticize them and do not respect their efforts, they will feel stressed. It is nothing to do anything with the low threshold. Well, it might help you that you can try yourself to believe, that many people will try to stop us intentionally and unintentionally. It is up to us who should we listen to and whom shall we admire. It is not your fault that you feel stressed in your work.