The phrase "leaning over backwards" means going out of one's way to help or accommodate someone else to the point of inconveniencing oneself. Some synonyms for this phrase include "bending over backwards," "going the extra mile," "making an extra effort," "putting oneself out," "sacrificing," or "exerting oneself." Essentially, these phrases all suggest that one is doing more than what is expected or necessary to help someone else. While being helpful and accommodating is generally seen as positive, there is a limit to how much one should sacrifice for others. Therefore, it's important to strike a balance between being kind and assertive to protect one's own well-being.